What is he on for substrate? Me and my bf recently put our bigger ones (who went off feed too) on aspen (over paper towels) so they could burrow to see if that gave them more security to start up eating again, and we've been having luck with that.

Have you left F/T feeders in with him overnight? Have you tried offering at different times of the day instead of just in the evenings (or whenever you offer)?

Maybe offer every 2 weeks over every week?