Trail camera defaults to 30 secs

I am now on to my second RSBB trail camera. The first had to be returned because after a while no matter what exposure time I set it to it defaulted to 30 sec. It then became very random giving videos as short as 1 sec.

The replacement camera worked fine up until a couple of months ago when it started to default to 30 sec. Has anyone any ideas why?

I have always used NiMH rechargeable batteries of either 2300mAh or 2800mAh.

I did read somewhere recently that rechargeables could mess with the electronics but there is no suggestion of this on the RSPB instruction/warranty.

Any help would be appreciated. I doubt if RSPB will replace this again.