Common Emitter: February 2018

I've got this monitor for free as previous owner gave up on fixing it.
Symptoms: monitor works fine at first look, but after hour or so it may randomly turn off or start showing image with weird colors (e.g. missing one color entirely). OSD menu has often random minor artifacts. It cannot be turned on again using ON/OFF button but with powered off entirely (detaching power cable) for few minutes it starts working correctly again for a random time. Sometimes image might get really weird:

From the posts on few forums this is common issue with this model and also with larger XB2374HDS and E2475HDS / B2475HDS. Two possible problems are listed: failure of NOVATEK NT68677UMFG chip (scaler) and failure of serial EEPROM (A25L020). Some suggested that main chips are just faulty and need replacement, but my plan for now is just trying to lower it temperature using radiator from old Pentium 4 motherboard north bridge. After testing for a few days this radiator seems to be helping, not fixing all problems (like not powering on after signal going down and then up) but reducing them significantly (hours of work but still need to cut down the power once or twice per day) - this might be just coincidental.

PAM8007 - class D power amplifier, 2 x 1.5W @ 4Ohm, 10% THD, 5V supply.

Audio quality is very poor as nothing separates the front and the back of the speaker. Perhaps some piece of plastic is missing from this unit? Otherwise this would be just poor design - sacrificing audio quality for like a dollar.

Monitor is using PWM for brightness control - it is working with 240Hz frequency right after brightness is reduced below 100%.

I've changed scaler chip for new one (from 2016) bought on ebay for ~$4. Although I've used hot air old one was rather hard to desolder. Also, despite used some protecting aluminum foil I've blown away 2 or 3 0402 SMD components near the chip - be careful when setting air flow.
Replacing scaler did not seem to make difference - monitor is still randomly shuts off, so my next planned step is replacing Flash chip. I have now new chip soldered and I've added piece of 3M thermal tape and small radiator just in case, but I think replacing Novatek was not necessary.
Update: Pm25LD020 finally arrived ($1.50 for 5 pieces) and then I realized I have no programmer for these low voltage chips (pickit2 with flashrom did not work for me), so I also ordered CH341A-based flash programmer ($2.50).
After desoldering original A25L020 I wasn't able to read anything making sense from it - it is possible I have overheated it, but I've used firmware from https://www.elektroda.pl/rtvforum/viewtopic.php?p=15640144#15640144 (iiyama ple 2274hds-b2 25l020.bin) and it seems to work. For programming I was using CH341A.
I don't see any problems with monitor at the moment.
This seems to be frequent problem with this model, but if you have to spend money to fix it keep in mind that this is not top of the line device - vertical viewing angles are pretty poor, PWM frequency is low (240Hz), speakers are just disgusting.

LED driver: OZ9998BGN, controlling 4 LED strings, up to 160mA per string, external PWM dimming input. My guess is that PWM frequency is controlled by scaler firmware thus might be not possible to change.