Texas BA II plus - Shutdowns during YTM calculation

Hi all!

I was doing YTM calculation on a problem using my Texas BA 2 plus.

As soon as I press [CPT]>[I/Y]
Screen goes blank totally. I try [ON/OFF] and other buttons too. Nothing works.

I tried the same on another unit of same calculator i.e. Texas BA 2 plus, same problem in that again in other calculator too.

It begins to work again only after I reset it using the [RESET] button at back, in both of them.

After resetting many times, I tried the different problem, but instead of computing [I/Y], I tried to compute [PV] where [I/Y] is already given.
Here it works properly. No issues.

I thought it was a battery issue, but functions other than [I/Y] are working properly and same problem is occurring on 2 separate devices is also weird.

Is there an issue with my calculators?, if yes please guide me what should I do in this case.

Thanks in advance.