Benq 2200w LCD monitor (intermittent issues)

[13hm13]

I recently got this monitor (manuf. 2008) from a dumpster.

Upon plugging in, it worked (on initial inspection) ... but all is not well ...

The screen intermittently flickers (moves) a bit horizontally. Also, the monitor seems to have problems with signal lock (screen blanks momentarily, with message of 'D-Sub' or 'DVI') I have it plugged via std. VGA.

More importantly, the front-panel buttons (including PWR) often do not work. Only way to shut off is to pull the AC cord.
Even more important, after plugging in (from OFF period of more than 1 hr), it is very hard to restart (pwr on) monitor.

Looking/checking inside, I de-soldered all the electro caps (none of which were bulging) and ck'd with ESR meter. All check okay, but I replaced a few that were just barely high ESR (only very slightly so). (Note: I only have one of those cheap (but effective) $10 ESR meters).

All the solder joints seem to be okay, and the monitor does stabilize a bit after being continuously on for a few hrs. While on, the image quality is just fine.

Any ideas as to the culprit?

Thx in advance!

[Whales]

Thoughts:

Bad buttons + signal lock instability: dirt & corrosion.

Signal lock instability: unstable power supply (caps?) or bad cable.  VGA signal is being fed in I presume? yes

[13hm13]

Thoughts:

Bad buttons + signal lock instability: dirt & corrosion.

Signal lock instability: unstable power supply (caps?) or bad cable.  VGA signal is being fed in I presume?

ALL buttons are un-reactive.Buttons are hermetically sealed type.
PSU caps check okay (please see OP).
Yes, VGA signal ... but problems is much more basic .... failing to pwr up (should do so regardless of input -- including the "Benq" logo splash screen).

[Whales]

"hermetically sealed type" ?  Can you share a picture?

Failing to power up: I have had some monitors that refuse to show anything at all, including branding, until you supply a valid signal.