[myTouch 4G Q&A, Help & Troubleshooting] espbasic:
MyTouch 4G keep turning off the display seemingly at random intervals and it stays off many times for long periods before it starts to behave normal. All other functions such as phone, alerts, receiving mail etc work normal while it is still in that state. In addition to the above, I also see quite a bit of curcial_oj_early_late_resume errors and a few others using OS Monitor to view the message log.

Here is what i have found out from 2 months of trying to fix it:

1. All buttons are always lit while this happens as if the screen was actually on (being used) - it even turns off the screen in the middle of using an application.

2. It receives calls, mails and messages as usual but the screen stays black. If I play with it, swiping to answer call, sometimes I am able to answer the call and talk normal.

3. At it worst times I stays blank/black even before the splash-screen and even if I try booting into recovery mode.

4. However, most of the time the blank screen appears just right after the splash-screen and the phone continue to boot normal.

5. Right after periods that it stays up long enough for me to see and flash a new ROM, it will behave for a while ... even hours normal ... then it starts acting up.

6. I tested it once while it was in boot mode and the screen stayed on for a very very long time without any problems (guess ruling out heat related?)

7. Even with different ROM versions it still occurs.

8. When it first happened was due to a battery drain (battery was changed to rule that out).

9. It behaves like a radical energy manager turning off the screen (why?) until a condition is meet. (recently used SetCPU to lower processor speed to minimum just in case of heat related ... did not work)

10. Power button has no effect on halting the problem once it is acting up

11. Problem seem to occur quicker after a ROM install as time progresses.

What has been done : (what OS routine or setting could survive this? ...)

1. Many complete wipes and re-installs (10+) via clockworkmod manually or ROM manager. (Many different Cyanogenmod ROM versions tried)

2. Changed battery.

3. SD card Format and tried different SD card. Also tried without SD card or SIM.

4. Tried different versions of busybox.

5. Lowered CPU speed to a constant 245Mhz

6. check if it is triggered by pressure, movement, or light ... (proximity sensor appears to work perfectly ok when I do take a call)

7. Sometimes the only way i can get the screen back on is to keep calling the phone and playing around with using the proximity sensor to trigger the wake. Takes hours of trying before that works though.

8. Tried "stay awake while plugged in" setting ... did not work

9. Tried running without adding any apps except those that came with ROM ... didn't work

10. Increased the screen time-out interval ... (even from ROM install it seem to ignore this time-out) ... if the screen stays inactive for 3 sec it shuts off the screen ... keep doing so until the interval get longer and longer

11. Used and Android antivirus to scan ... no problems found

12. Recently changed to Virtuous Unity which helped be bring it back from display off state with a press of the power button (pressing once to stop it -all button lights go out, and once more to bring the display up) ... but still turns off display frequently.

... few other things tried, but you get the idea.

Oh yea, I perm rooted from a while back and it worked perfectly for months before this started happening ... it started before I even considered to flash my first ROM.