iPhone 7 DFU mode fails because firmware file is corrupt?

I got a full storage notification on my iPhone 7 a couple of weeks ago (I get this often and normally delete apps/videos and it is fine after). It was also being very laggy, not sending/receiving texts or iMessages, and when I tried to go on Snapchat it kept asking me to agree to some T&C user agreement from 2019, but exited the app whenever I tried to agree to it (not sure if this is relevant). I turned it off thinking it might restart normally but since then it has been stuck in boot loop.

My Mac doesn’t recognise it when I connect it by USB. I’ve tried recovery mode and DFU mode which work up until my Mac has finished downloading the iOS software. When it then tries to actually restore the phone, I get a message that says it cannot be restored because the phone’s firmware is corrupt.

The phone is not jailbroken, has no water damage, has never been repaired/had any parts replaced, and was working fine until this happened.

Is there anything else I can try or is it a lost cause? Or am I doing something wrong in DFU/recovery mode?