mobile

I'm helping a friend with her S3 i9300. It was running very sluggishly and starting in the last couple months she's been having a sleep of death issue.

It works fine (albeit slowly) while she's using it but when it sleeps for more than 10 minutes it doesn't turn back on without a lot of trouble or a holding down the power button and hard resetting. Every once in a while it only boots if I go indirectly through download mode.

I've confirmed with the play store app that she does NOT have the "insane chip" involved in the SDS issue. I've also factory resetted, rooted, tried flashing a custom kernel, a custom TW ROM (S5 sensation) and now an AOSP ROM (resurrection remix) and the problem persists.

Looking at other users' suggestions I took it apart and cleaned/played with the power button, even replacing it with the one from my old t999. Still the same.

I'm at a loss at this point. Has anyone run into this issue and found a fix I'm missing? Thanks for the help.