Refurbished ABS module worked fine for two years until mostly permanent trifecta appeared

Hi, I had the classic Bosch 5.7 ABS we trifecta two years ago where trifecta appeared after a warm engine etc, after this the module was refurbished. Since then I’ve had zero issues until 3 days before my MOT test.

Refurbisher has lifetime warranty, so I sent it back to them. They tested their module on their test bench and found no errors.

Now I have an issue where ABS/DSC/brake warning lights are present 98% of the times I start the car. Speedometer, cruise, odometer still works, INPA/ISTA can communicate with DSC.

Randomly, hot or cold engine, DSC etc just works and lights are gone. This seems to last until I turn off the car again. When it actually works, ABS, traction and stability control is active.
Can’t remove lights by deleting error codes.

INPA/ISTA shows 000015 «Fault in DSC control unit» and 000061 «DSC: Steering-angle Sensor, identification», sometimes. Deleting error codes doesn’t do anything to remove lights.
Running steering angle calibration, via ISTA or dsc57.prg test_lenkwinckel doesn’t help.

Steering angle sensor and wheel speed sensor analog outputs seems to work fine. Angle gradually varies with steering input, and 4 wheel speed sensors show about the same, correct, uninterrupted speed. Tried starting while charging at 14V with charger.
Brake fluid level OK.

For the 3 times DSC lights were off during the last two weeks:

1st- for a 10 meter reverse drive out of the garage after receiving module back from warranty claim, then failed again 10 minutes later on next start

2nd- worked again a morning after leaving it for 10 hours. No physical changes during that time, just screwing around in inpa/ista
Car on for 3 minutes, drove 200 meters, turned off car, turned back on 5 minutes later and lights are back

3rd- Lights gone after turning off car for 3 minutes, warm car. Tried abusing car on the gravel to force test abs/dsc/tc to get lights back on, all worked nominally while driving around for 15 minutes. Turned off car, after 2 minutes it reappeared when turning ignition to stage two.

I am wondering whether something is happening during the initialization of the DSC right after turning on ignition? When it works lights turn off after the self test.

I bought a junkyard DSC unit to test which should arrive in about two weeks, even if it has a classic 5.7 heat cycle soldering issue it should behave differently if the module is at fault.
Anyone got any suggestions on what to test the next time DSC suddenly works again?