4x4 help

[Welderman85]

I have a 2000 Tahoe. I had in the snow in some snow and 4x4 worked great. I parked it let it sit for a while then went to move and it wouldn't go in to 4x4 anymore. The lights just flashed and the dash said service 4 wheel drive. Now two days later my son left the lights on and killed the battery. Now it wont do any with 4x4 no lights anything. Where do I start to fix this . Thank you

 

[swathdiver]

Start with the battery and then get a good scan tool that can read the codes or a bi-directional tool that can test out the 4x4 actuators and switches.

 

[MrBalll]

What did you do with your battery and did it help any?