HP L2335 Monitor (Pixelworks PW172-30V Scaler)

[Sceptre]

I have an HP L2335 Monitor that won't start up.  The power LED (green) illuminates when AC is applied, but there is no picture (not just no backlight) or response to key presses.   DC rails from the power supply board look OK.

Service manual https://www.electronica-pt.com/esquema/monitores/aoc-esquema-monitor/aoc-service-manual-hp-l2335_a00-monitor-lcd-13887/ troubleshooting chart says to check for key scans.  The OE for that buffer (CS0, which comes straight from the PW172 scaler device) appears to be stuck high.  So I check power to the scaler; all rails look good.  Clock (14ish MHz) is present.  Mode bits are in the states indicated by the schematic.  No sign of reads from the EEPROM (even on AC power up), but the scaler is reading flash (AT49BV8192AT-12TC) - there's activity on ROMOE (~G) and some address and data lines.  It appears to be cyclical and continually repeating, based on the trace on my analog scope.  No apparent activity on the scaler's RS-232 port.

If I had access to a logic analyzer, I'd take a closer look at the flash accesses, to see if it's polling for some missing signal.  I haven't found firmware online for this monitor, so if the flash is corrupted, I'm out of luck.  Another possibility is that the CS0 line is open between the scaler and the key buffer (so it's cycling in the key scan but not getting any presses), but that would likely be an open connection at the BGA (I don't have a rework station either).  There's a board available on ebay, I could take a flyer on that.

Any tips, insight, etc. on this model?

Thanks!