WHAT??

No complete teardown of the old camera?

Catch that up immediately, please!
Btw.: On still cameras, Canon often changes the compatibility of the battery pack, also.
One good reason is a better built-in capacity monitoring, for example.
Sooner or later, cheap compatible clones show up on the market.
Don't upset yourself, the clones will be pretty cheap again, compared to the original Canon ones.

Frank