Error 37001 IRC5 Compact 1st gen

Hello,

I have a IRB 1600 working with a IRC5 Compact 1st Gen.

I was doing some test on program in manual mode and suddendly the robot stopped while executing the program.
Now I have a 37001 error on teach-pendant each time I push the dead man switch. I cannot energize the motors.

"Error in 37001, contactor switch error. Motors ON contactor 2 or 1 in drive module 1 failed to close when ordered."

I readed a lot of threads on the topic, but I am still stuck in the resolution of this issue.

To resume :

I opened the top panel and watched what happened : K42 pull in and pull out shortly after, K43 don't pull.

Then, I monitored the 24VDC coil voltage between A1 & A2 for each contactors

- K42 : coil OK - 24 V OK

- K43 : coil OK - 24V NOK.

I checked voltage on my XS9 SAFETY & I/O INTERFACE :
All voltage monitored are OK

I am wondering what to check now, is my Safety board is bad ?

Help is welcome !