keyboard + other issues

Hello,

I will try to add as much information as I can. The main problem is I don’t know how all the issues are connected to each other.

So, some time ago a problem with key E appeared. Sometimes it didn’t work, sometimes, if push several times it started to work again. Then it could type several E(s). This was a rare case at the beginning. Eventually, mac started to type E at random times, but not when the key is pushed.

So, I bought new keyboard (it looks good, but definitely not Apple) and replaced existing with new one.

1 week everything worked perfect. Then the keys Left Shift, Backspace, Left and Right Arrow keys started to do similar to what happened with E on old keyboard, until they stopped to work at all. (Bad left shift makes it impossible to reset SMC)

At this point I had to clue how to proceed. But even before the keyboard replacement, the battery was pretty bad (1100+ cycles and “Service Recommended“). Sometimes it started to shutdown even on 50% charge.

So, I decided to replace the battery. I just did it. The battery looks like original Apple manufactured battery. The results:

1. Keyboard still has the same issue - multiple keys are not working.
2. mac didn’t start at all with new battery, but started after I plugged in the cable. Then I unplugged it, shutdown - and now it does not start at all, with or without the power cable. The charge was about 70%.

Another piece of information: this mac has dual graphic cards. I’m not 100% sure, but it seems dGPU is not working. I tried to force mac to use it and Monitor even showed that dGPU is on, but none of the applications were using it. I’m pretty sure I saw Chrome was using it a long time ago.

There was no spill done to this mac.

What could it be? Dying motherboard? If so, is there a good way to check it?

Btw, I could run Diagnostics after keyboard replacement - no issues were found.

Thanks