No display response, red LED blinking

[Markus94]

So a friend of mine told me his phone wasn't charging, I asked him if he still had a warranty on it and since he replied no I asked him if I could take a look at it.

I disassambled it to check which parts were broken, but everything except for the USB-C hub and the plastic bracket fixating it was fine, so i put it back together, ordered a new flat cable which has been delivered today. At this point, if I'd plug it to a charger, it would still occasionally turn on the screen and show the "low battery" symbol.

I put in the new flat cable with the USB-C attached, fixated it the best i could and checked if it was charging. Now the LED is blinking red in a long light - long pause pattern when it's fast charging, and is lit constantly when plugged to the PC, but the screen doesn't turn on. I've also managed to turn the LED blue, to which xperia companion responded with "device locked", so there shouldn't be an issue with the mainboard or software, but there's still nothing on the screen.

Did I accidentally break the screen cable or is there anything else that I could have done wrong, like forgotten to attach something?

[Markus94]

Edit: The LED stops blinking after a minute or two

I've tried both cables, no difference

[MarlonUk1]

warranty or not, only authorized sony service centers are trained to repair the phone.

the red blinking led means it might have a drained battery

try to charge the device using the supplied wallmount cable and adapter.

hook it up for more or less 2 hours then attempt to reboot...

[Markus94]

I actually think it does boot, there's a short vibration after I hold down the power button for 3 sec, just nothing showing on the screen, after which I disconnect and reconnect the battery so it doesn't drain while charging. But I'll try that, thank you.

[Markus94]

So basically, the question is can battery be so bad that it can't supply the display with enough current to work even though it should be charging?

[MarlonUk1 · Accepted solution]

i dont know why, but sometimes it gets depleted that it wont even power up. and Xperia devices are not configured  to draw power form the charger bypassing the battery.