08 sierra 1500 4wd no go

[132operator]

hi I have a 2008 sierra sle 4wd, few weeks bak I left interior lights on n run bat., dead after jump strt now it says service 4wd an wont go to auto 4wd, 4hi, or 4lo, jus two wheel drive. had diagnoses run and sayd lost contact between transfercase and power source. can I remove motor from back of transfercase and engage 4wd manually until I find exact prob or can yall give me some hints maby to reset this... ????
Thanks Andy