I just got a CoolBaby RS-90, branded by "Mars gaming" (product page: https://www.marsgaming.eu/en/retro/mrb-portable-retro-console_mrbb
). As I guessed it's just a rebranding, I used the pinned guide to install OpenDingux.
Everything worked fine, except that since the first message from the flasher, everything shown on screen is extremely dark, to the point to having to tilt the console to be able to read the texts on screen.
I thought it was something related to brightness, so after installing I tried in the configuration with several brightness levels, but none fixed the problem; I can see the brightness change, but the displayed image is still too dark.
Then I thought maybe I have a 3.0 version, so I started from the beginning, but this time I used the 3.0 flasher, it installed OpenDingux ok, but with the exact same screen problem.
Then I tried updating OpenDingux downloading the latest OPK file, it installed fine, but the problem persist, but with the added problem that now I'm unable to copy files from the computer (it tries, does nothing for several seconds and then the USB device gets disconnected from the computer).
Another thing I noticed, is that on none of the versions of OpenDingux I can see the contents of the microSD card. It's an old 128Mb card formatted to FAT32. Do I have to format it another way?
Please help, as I don't have access to the original firmware, and while that one was extremely bad, at least the screen showed bright and colorful.