M5.2 = EWS2
M5.2.1 = EWS3
ISN (EWS2) in M5.2 is written at 0xFD3D, 4 Decimal digits in ascii, which need to be converted to hex
ISN (EWS3) in M5.2.1 is written just after this at 0xFD41, raw hex from the dump, 2 bytes repeated three times.
Address offsets are for full reads from the flash, part read will not show the EWS3 ISN, only EWS2 ISN from M5.2