Starting the Chinook after letting it sit a week

Reach for battery cleaning brush before reaching for wallet...

Clean all battery connections thoroughly. Hopefully there are no bolt together emergency battery terminals.
Then when you think you're done - you aren't. Follow the negative battery cables where they attach to the chassis frame, unbolt them, and make bright the cable leg and what they bolt to. Smear grease atop to stop corrosion.

Charge batteries, then wait and see.

Do you still need your wallet?