As you remove the motherboard, there's a chance it'll short-circuit against the battery connector. Block this connection to prevent damage.

Slightly lift the left edge of the motherboard.

Insert a playing card or similar object between the battery connector and the motherboard.

If your card catches on the underside of the motherboard, wiggle the card until it slides fully underneath.

If you're reassembling your Surface Pro with a new battery, remove the playing card now.