Is your kicker electric or pull start?
An electric will not have to be grounded.
Also, how many elecronics do you have hooked up to one battery? The Box may not be drawing enough power to operate properly. The box drawns a small amount, but this can may a difference. Also, it may be a simple as cleaning all connections. I was baffled last year when I was running at negative. Cleaned all the terminals and was back in business.

Downriggin'
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"If you are not scratchin bottom, you ain't fishing deep enough!" -DR

Puget Sound Anglers, Gig Harbor Chapter