No HDMI output signal, composit DOES work

Hi, I bought a broken ps3 to repair (mostly for fun). The console was really dirty and dusty and a bunch of corrosion on the insides.

Power/eject button fixed: When I got it, the power and eject button where not working. After cleaning those contacts with IPA, they work great again.

Video output: At first, I got no video signal at all. So, I tried the hold power button to reset the video signal solution ... and it worked! For the composit video signal. Then, I connected it to HDMI and changed the output. At first it worked fine ... some time later I just got a blink of a distorted HDMI screen and after that ... nothing.

Possible solutions tried so far:

Holding the power button to reset the video signal

Tried another HDMI cable

Tried HDMI cables on other devices (and they work fine)

Cleaning the HDMI port

Inspected the HDMI port, seems secure to me (could I test it with a multimeter?)

Suspections

Could the HDMI port not making full contact with the motherboard? (needs reflow)?

Could the HDMI IC (mn8647091) chip be broken? How do I go about testing it?