You should easily be able to fit a replacement on the existing back plate.
See the reviews here:
https://www.amazon.co.uk/gp/aw/d/B002NAGI2E
I had a similar issue with an ESI programmer. On the basis of having nothing to lose I took it apart and fitted a new lithium coin cell but I future proofed it by getting a suitable coin cell holder and using an ordinary coin cell without solder tags.
Simple enough but there again, I spent many years as an electronic test engineer.
Eehhg
October 2021