NVRAM backup and restore

01SD card

Service SD in the slot labeled on the GW+ board (usually SD2 for NVRAM, SD1 for firmware — read the silkscreen, it varies). FAT32, not a firmware card full of other packages if you can avoid it.

02Upload SP5-824-001

SP5-824-001 NVRAM Data Upload. Wait for completion. Pull the SD and label it with the serial and date. This is the real NVRAM backup — 5992 is SMC dump, not NVRAM.

03Replace the board / NVRAM

Power off. Swap. Power on into SP.

04Download SP5-825-001

Same SD, SP5-825-001. The file serial must match this machine. Confirm serial and total counter after reboot. If serial is wrong, stop — serial-set bulletin, do not leave a cloned serial in the field.