Was the battery charger breaker on? Shore power will only operate 120V things, A/C, microwave, electric stove, hot water heater, frig (dual volt). All 12 V wil still be on battery power.
Some boats have jumper terminals next the the battery switch to jump in 12 V.
Where the hatch lift ram attaches to the deck there should be an access port to allow you to undo the Rams pin then you can manually lift the deck.
1997 2400 SCR
5.7 Vortec / Bravo 2