Hi.

Corrosion to the board, previous work by customer, been through UC

PPBUS = 8.62V
PPBUS_S5_HS_OTHER_ISNS = 1.2V
PP5V_S5 1.2V


Oh, found the problem. I'll post this in case anyone else has a board like this.

Someone had removed C7583 and torn the pad connecting to PPBUS_S5_HS_OTHER_ISNS...
The connecting via comes from that pad through the very thin trace / pad of C7583. no idea if this is common but it may help someone if board has been fucked by customer.