Xperia z5 sudden death / won't charge / won't turn on

[RaoufBR]

Hello everyone .. so my xperia z5 battery lately wasn't holding up well until last week the phone didn't want to charge it was at 60% so i kept using it because i needed it and i wasn't able to charge it at that time til the battery drained .. when i went home i plugged the charger and it didnt respond it just makes the charging symbole then tries to start and fails at sony logo then restart again so ithought the battery is dead and needs to be replaced , i took it to a sony repair center and i got it replaced immidiatly , took the phone home plugged it and it didn't want to charge  so i took it back and they said nothing's wrong with the charging port flex you need to replace the motherboard, i didnt do that took the phone back read some threads tried every methode .. the volume up and power buttons for 10 for 20 for 30 second the 120s OFF button reset /volume down every key combination for every duration and it dodn't work it doesnt connect to sony companion it just shows battery charging logo (but it doesnt charge) then immidiatly tries to boot and fails and restarts again .. any solutions for this problem? (sorry for long text)

[Llamakit]

I have this exact problem and it happened in April of 2019 as well. I've replaced the battery and the charging port and my phone responds exactly as described in the above post. After getting to the Sony Xperia logo the screen shows the android logo and then the Sony swirls. The swirls stop, the screen goes dark except for a large battery logo and then goes fully dark. The charging light remains off. Until the phone went dead I was only using it about once a week on wifi. No sim and no sd card.

Edit: I've had many Sony phones in the Xperia line - Z, Z Ultra, Z2 (which survived much rain and even a fall into asphalt at 20mph), as well as the Arc S. The Z5 was the first Sony I didn't root and install a custom rom. I suspect this is a software issue.