Depending on the model of electric tongue jack that you have, access is slightly different. Basically, you need to remove the top of the power unit to expose the top of the driver shaft. At the top is a bolt head that can manually raise and lower the tongue foot with a long handle wrench or ratchet.
SuEllyn & Brian McCabe
WBCCI #3628 -- AIR #14872 -- TAC #FL-7
2015 FC 25' FB (Lucy) with HAHA
2005 Suburban 2500 Quadrasteer (Olivia) & 2011 Silverado 3500 (Fred) with Outfitter Truck Camper (Ethel)