6i25+7i77 CR16 staying red

Last news:
I've found this DB25 cable, so I've tried it: reloaded 7i77x2 firmware, plugged everything and .. same story.
Refuting a dead 7i77, I had a spare HDD; installed wheezy with linuxcnc 2.7 with no luck.
I even tried to power the 7i77 by the 6i25, it didn't change anything.
I guess it's really dead.

Beside a RMA form Mesa can something can be done ? I expect shipping cost from France to USA is quite high... maybe buying a new one will be cheaper.

Can somebody explain to me what is this driver configuration string thing ?

And more important: what can be the cause to a dead I/O field ?
I don't want this to happen again and want to find why.

Things I could have done wrong, but I have no memory of this:
-Reverse polarity on I/O field (very unlikely, should I see some smoke if this happen ?)
-Wrong custom flat cable, most likely reversing connector or cutting the wrong side since it's 25 to 24.
-Messing with jumpers to power 7i77; W1 on 6i25 and W2 on 7i77.
-I'm powering I/O field directly with a +24Vdc power supply with no relay like described in the manuel. Slew rate to high ? I guess I could check it with a scope just to be sure.

Anyway thanks for helping me.

Did you try both 6I25 connectors in case there's a bad I/O bit?
If the 7I77 is bad, we can ship you a replacement.

We have occasionally seen ( in maybe 2 or 3 out of 1000s of cards)
DSPICs that forget their programming and that may be whats
happened here.

Yes I've tried both P2 and P3 connectors.
P2 connector with provided cable, tested with 7i77x2 firmware.
P3 with a custom made, tested with 7i77x2r firmware. (tested only on debian 10, but I don't think it's matter anymore)

I have a JTAG-usb and PICkit3-usb if it can help.

You could try reprogramming the DSPIC that would at least determine if the DSPIC forgot its programming or there is another issue. If you cannot get it running, send an email to tech@mesanet.com and we will assign an RMA# and send you a replacement card

7I77 Digital side DSPIC firmware:

freeby.mesanet.com/7I77DS14H1.HEX

Thank you, I will grab my PICkit at work and reprogram it.
Is it fine if i'm soldering a connector on the back ?
Square pin is number 1 (VPP/MCLR ) ?

You can solder a header, but its not required, you can just insert a header
and apply gentle sideways force to guarantee contact of all pins while programming (this is how we program them)

Programing connector pin-out:
1 VPP (Square pad)
2 3.3V
3 PGD
4 PGC
5 GND