I think the eeprom has problems. The nvflash utility uploaded the firmware but it can't read and save it after. It gives 0 bytes size file, and Invalid data. But it find the card as suppose to, as Geforce2 MX/MX 400 (10DE:0110) on the AGP bus.
I think I'll buy a new eeprom I don't know if I've got one of these.

I tried reading bytes from the board eeprom and gives a series of FF and after that all 00.

EDIT: I've seen some of these cards (but with a different pcb later revision while identical) has the same 32pin eeprom socket but with a 28pin Holtek eeprom installed. I've got some of these I tried to see if nvflash see it but it does not. I suppose it might need some pcb different layout for it. Meanwhile I've read a sticker under the eeprom that says "3.11.00.07.00" which is the same bios I've downloaded so at least I've found the exact version. The 28pin eeprom thing could have been interesting. Many cheap Rage cards had that eeprom to try. EDIT: because it's a one-time-flashing memory which can't be flashed again. Probably they just used these cause cheaper who knows. Anyway also the SMD components above the EPROM are different so I could not make it work anyway I suppose.

EDIT: some update with the SST eeprom: with nvflash 5.15 I sort of updated the eeprom (after I had just bought a new empty one...perfect... 🙁 ) and now it seems to read bytes into it.. but still no signal, no sound.. I noticed that the nvflash of the original manufacturer is customized with Prolink name while an old version v3.x. Now that theorically should find an existing written value inside the eeprom I might try using again the older one to flash it again maybe it use some custom way for it. But I begin to suspect the eeprom is not the problem at last. I might try to change capacitors. The GPU anyway sure get warm almost hot without the heatsink so I suppose the voltage arrive to the GPU and the power mosfet works.

EDIT: new tests and old problems... I booted again with a Virge/DX PCI card together with the Geforce2 MX on the AGP bus and in the same pure msdos situation I could read and save from the eeprom and after a while not anymore with again an empty one even without restarting.. I suppose the eeprom might have some problem anyway beside maybe not the only one. So once I'll get the new SST chip I'll try if this doesn't happen all the times which might mean something else is wrong. I tried to clean the eeprom contacts but were already ok like the socket ones. Could it be the eeprom voltage that arrive or not depending maybe on something else?

UPDATE: I changed mainboard to mix the variables here and went for a KT133 old SDRAM based board. Also I removed again the eeprom and cleaned again the contacts. Now it seems again to find values inside the eeprom and saving the file to the hard disk it seems the same size of the one downloaded. It looks like a eeprom reading problem but still no signal no sounds no boot. Interesting I've a Riva NV4 AGP 8MB from Creative that doesn't work too but that card sure gives specific beep sounds before not displaying any signal but even the official Creative Flasher seems to not find that eeprom which I suppose is really gone but soldered... This situation seems different.

I would give a re-cap a shot, I had a mx200 which was giving problems (opengl artifacts and crashing in particular), despite all the caps looking fine, after replacing them it works flawlessly.