T5577 & FDX-A ... how do i reset the T5577?

So here’s a dumb question

Trying to write to a cheap Chinese glass tag
(Not for implantation, possibly embedding in 3D prints or something)

I can’t seem to write or read the stupid thing

I actually busted out the field detectors to look, and the flipper has great field…

I figure there’s 2 possibilities.

It’s garbage, or not actually a t5577 / not rewritable
Or
I’m doing something wrong and missed something obvious

I’m assuming that whatever it’s set to, if I write to it … it should changed it to the format I tell it right?

It’s marketed as a pet chip using FDX-A, not sure if that’s actually a mode or not… but if I were to write to it, say EM or hid prox, it should become that right?

Or do I need to use a proxmark to change modes or something?