I went to the trouble of actually lifting (severing, really!) the write protect pin, so I'm not sure whether flashing would work or not without such intervention. That tool didn't seem to work for flashing until I managed to finagle the thing into ISP and brick it, but maybe it could be made to work more reliably?
I suspect the firmware originally made for the RTD2550 (the chip I have) is part of the problem in enabling ISP mode. Uncertain. Will test on Windows later now that I have a good dump to restore from.
The Linux PC I've been using has an Intel graphics chip, which could be a discrepancy in terms of flashing - even though the 2550 backup firmware flashed and restored the monitor to normal functionality. My Raspberry Pi is on router duty, so I'll have to test that later.
However, I think it might be more likely that either of the Laser Bear firmwares just isn't compatible - because when I tried to flash the RTD2556T firmware, it became 'bricked' again. Maybe that's partly the Linux tool; I might do more testing on Windows with RTDTool now that I have a working backup file and method of restoring in case I brick again.
Since we now have a working backup firmware, I'll go ahead and link
the copy of RTDTool with the GFXI2C interface driver I was able to get the monitor into ISP with - Doozer said he could flash the Laser Bear firmware onto his own monitor with no trouble using the hardware ISP programmer. (My monitor is the dual HDMI board, if it matters.)
Doozer, how did you extract the firmware .bin files in the post where you talk about their contents? If we could cross-examine those files, we might figure out what's going on and how we might add one feature or another to the other chips.
EDIT: It seems like GFXI2C is fully capable of erasing the chip, but very much has trouble writing to it. It invariably fails at some point. Perhaps there's a newer version of RTDTool floating out there somewhere? I don't have any hard info on the RTD2550 like a datasheet or anything to hand, unfortunately.
It seems like there's no partitioning between user settings and system data, either; some settings have been retained between flashes at times, depending on how the flash went.
EDIT 2 Does anyone with the Laser Bear firmware or a 50 Hz compatible monitor have their EDID (including any extensions), perhaps? That might help people with PAL-based issues, if it works more generally.
