OK a couple of comments before we get started:
***After taking apart this system I DO NOT RECOMMEND anyone else do this unless you are extremely experienced in small electronic dis-assembly and you have NO other option to fix your hardware issue!***The internal ribbon cables are extremely fragile and low budget. This system clearly was meant to be assembled once. These parts are not of the caliber that you will see in main stream products. do to this they can tear, strip or snap off the board very easily. they can not stand being disassembled multiple times as they will wear out extremely quickly!
***In their defense they are perfectly suitable for their use and are sturdy enough for the gaming that will be done on the product, but once hooked up are not really meant to be tampered with.
OK on to the Teardown.
First thing I noticed was that the QC and GB size stickers serve no real purpose, as they are not covering a screw hole like they are meant to. they can be removed if you don't like them.
I have removed those stickers and the screw cover plugs in the first picture.
http://imgur.com/hzzdlFx**upon accessing the screws i noticed that 2 of my screws were actually almost completely NOT screwed down and just hanging in their sockets by a turn or more, not cool. (top left screw and bottom right screw)
anyway moving on. the 4 screws here are really not doing much to hold the back plate on the unit as that i really being held on by the 6 plastic clip points on the inside that need to be popped. to do this you will need to carefully put a paperclip in the mini hole on the underneath of the system located near the power light. (just to the left of it) pry this up a little to pop the first clips and then use a spludger to work your way around the system popping the rest.
**be very careful when inserting the Paperclip as there is a MICRO battery not too deep in that hole that I snapped off the motherboard when prying to pop the first clips. I will show this to you in a later photo, (had to solder it back on)
** also when the clips are all popped you will want to lift slowly upwards towards the L and R buttons as they are attached via a cheap ribbon cable to the motherboard as well as the battery.
http://imgur.com/JOCt2i1Now we get a look a the motherboard in the above photo. I have already de-attached the battery that would normally be sitting right in the middle of that photo. It is attached to the underneeth of the back plate by double sided tape.
** you can see how small and thin the ribbon cables are for a selection of items here. the L and R buttons the analog sticks (that are their own item) and so on.
Below is a picture of the units battery. Notice that there are NO listings of manufacturer or Voltage ratings. This kind of sucks as it will NOT be easy to replace with another one without that info. I should also mention that the soldered red and black contacts to the battery are very very weak and can easily be bent or snapped off due to cheap solder contacts.
http://imgur.com/uHoge22Here is the picture of the snapped off MICRO battery that was in the hole were we pried the unit apart with the paperclip. I have NO idea what its purpose is (maybe a CMOS battery?) who knows but I later soldered it back on.
http://imgur.com/729Z1T0Here is a general overview shot of the back panel that was removed that contains the L and R buttons. Not much to say here except that the ribbon cables being used for these are VERY FRAGILE AND THIN.
http://imgur.com/LSaRYuqHere is a closer look at the design of the L and R buttons, they look to use a miniture version of the standard arcade microswitches and not your standard Nintendo or Sony microswitches.
http://imgur.com/uLWT98kHere is a side shot with the bottom panel off showing you the WIFI antenna or lack there of. its on the right side of the unit beside the right analog stick. This area will almost always be covered by your right hand which will lower the atenna's range as well as the paint that also disipates the signal. I have done many custom paint jobs for home consoles and portables and one thing i learned real fast is that painting multiple layers onto plastic that has a WIFI antenna underneith will GREATLY reduce its signal range if not completely kill it. This should also help explain why the paint quality is SO thin. if it was much thicker it would make the WIFI range even worse.
http://imgur.com/qQeH8zqHere is a good shot showing you how fragile the plastic is and how easy it is to snap the clips on this system. these clips are intricate to holding the back shell on tightly and as i previously mentioned the back screw do little to hold that plate fully in place.
http://imgur.com/x1YIY0FHere is a shot of the Left analog stick and its ribbon cable and the Screen ribbon cable right beside it. i find it odd that they decided to let the screen ribbon cable go over the back end of the Left analog stick, but whatever. Take note that both these ribbon cables are EXTREMLY FRAGILE and should NOT be tampered with. the ribbon cabling is extremely THIN and very suceptable to tearing.
http://imgur.com/ke8xG5YHere we have the controller rubbers with the Primary motherboard removed. they are the standard rubber membrains you would see on most nintendo gaming products. Not much i can say as these are standard parts. I will make one note that for people having issues with their diagonal movement with the arrow key i believe you have a mis-seated rubber membrain. the arrow key membrain and the X, Y, A, B membrain have a housing rubber frame that helps seat the membrane in place and hold it there. its not uncommon for this to get not fully seated or shifted during assembly when they flip it over to screw down the mother board. this is a common occurance with offbrand controllers. and would require a teardown to re-seat the controller membrain to its proper position. (at your own risk of course as this is just a theory of why you are having diagonal issues)
http://imgur.com/wMfOIUDHere is a shot of the primary motherboard by itself. you can see that the android buttons are the bottlecap clicky kind while the directional key and controller buttons are of the classic NES kind with the mushiness everyone has described.
http://imgur.com/kfoe93QHere is a closeup of the fixed MICRO battery after i soldered it back on.
http://imgur.com/44fddmEAnd here is the unit booting up after it has been re-assembled. (with fingerprints all over the screen)
http://imgur.com/btEGmiN****Final thoughts. Regardless of how low budget the parts being used are, this is one of the best NockOFF systems i have ever had the pleasure of owning. I have been buying these type of systems to play my EMU's for years. I still have a GPX32, a GPX32 WIZ, This system and a JXD s7800b.
All of these systems will have similar build quality due to the inexpensive Chinese manufacturing. But that is why they only cost $100 to $200 and not $350 to $400. and by and large the community that buys this kind of stuff understands that.
As for repairablility of this unit, that can pretty much be summed up as 0. I am seeing a lot of proprietary parts like the custom L and R clickers, the NON-Descriptive battery, Etc. If i had access to these parts than YES i would say it could be repaired with some effort, without access to these parts and just going by what you could GUT from something else...... NOPE.
In the end I again DO NOT RECOMMEND taking your unit apart as the internals are VERY FRAGILE and even with my 20yrs of engineering skills and micro modding portables experience, I still managed to damage minor stuff that i luckley could repair.
I hope this has been informative to you all.