[MTCD  Android Head Units Q&A] Perepandel:
Hi,

First of all, please excuse me if I have post on the wrong forum. I really searched a lot for a similar question but haven't found it. My unit's MCU versoin is MTCE_CZ_V3.10_2, so I don't know if it's really a "MTCE" head unit, but I don't see a MTCE specific sub-forum (by the way, what does the MTCD, MTCB and so on nomenclature mean?). I got this unit from AliExpress about a year and a half ago, it's a 4 GB, octa-core cortex-a53@1.5G version, with 64 GB internal memory and DVD, for Vauxhall/Opel Corsa, and this is the current (updated) product page for it:

https://www.aliexpress.com/item/32789005299.html?spm=a2g0s.9042311.0.0.27424c4dbyAN90

It currently displays a PX6 version; mine is the PX5 one.

Well, the problem with the unit happend a few weeks after I installed it on my car. Suddenly, one time, when I started my car's engine, I noticed the unit wouldn't turn on. No matter how times I attempted to reset it, it wouldn't do anything (although when doing so, through the small pin hole, colorful led light would cycle through the cover.

I contacted Wondefoo and they sent-me a an HTC-PX5--REV12(LPDDR-221), 20190515, board replacement, exactly like the original one. After replacing it, the unit started working again.

In january 2020 this happened again. Tried exchanging it again with the original MCU; nothing worked.

Nearly two months later I attempted the same procedura and this time it worked - the unit started working again.

My bet is that something is causing this unit to get stuck, and after enough time passes and the capacitors get emptied and the DRAM erases, it's able to "recover" somehow.

Maybe 6 months ago, this happened again. Out of frustration, in the middle of a drive, once I started pushing all the buttons randomly. Finally, I don't know by which combination, the unit turned on, displaying a recover menu. I don't know how, simple choosed to restart and it became working again.

Some weeks later, after getting unresponsive again and trying the "random button push" procedure, the menu showed up again. This time I attempted a factory reset and got the unit working for severl weeks.

Finally, my unit died for the last time about two months ago and I haven't been able to recover it by the "pushing buttons" method, neither by disconnecting it from the power source and reconnecting days later. I came back to the original radio player, which is a hassle as the CD player is also broken.

I'd like to try echanging the MCU with the spare one; I'm almost sure that it will work again, but before doing so I'd like to assure that I won't find myself in this situation again, as it's a waste of time. Maybe the problem is known and you can recommend me a software version / update that would prevent this from happen again. Maybe there is some sort of hardware mod that can be attempted by replacing some component. Maybe you know how to "hard reset" it from some motherboard pins, maybe where I could mount a switch to do so when the unit becomes dead, or maybe you can tell me the proper key combination for the recovery menu.

I've also found some firmware pages, namely https://yadi.sk/d/umCvHqCDzHccr, with a long list for several models. It looks more or less clear where to get the MCU firmware, but for the Android image it's a bit more complicated. If I enter the RockChip PX5 Android 9 folder, then HTC subfolder, there are several HTC4_XXXXXXXXXXX, HTC5_XXXXXXXXXXX and HTC_XXXXXXXXXXX options, and the same for RockChip PX5 Android 10 (assuming that there were an Android 10 update for my hardware; it came with Android 9 if I'm not wrong), so I don't know which one to attempt.

PS: the "reset" little hole never has really worked for me in this situation. It just will cycle to RGB leds if I push it with a paperclick and, while pushing, press the "on" button, and they will shut off when I release the button, but that's all.