w639 intermittent no crank,no start,no consent start no comunication

Hi everyone,


Iam dealing a strange intermittent issue on mercedes w639 with om646 engine
edc 16c2 ecu(bosch 02810120650
ISSUE sometimes the vehicle refuse to start
the instrument cluster power on normally
ezs gives terminal 50
however no fuel no craank no start
during issue ecu no communication over obd
consent to start off
tested donor sam same intermittent issue
reflowed solder joint inside e