InDesign file crashes instantly when opening

Hi all,

I'm currently job hunting and urgently need to edit my portfolio, but the InDesign file just won't open anymore. InDesign crashes immediately when I try to open it. I'm working on a pretty old MacBook (2013, running Big Sur 11.7.10) and I can't download the latest version of InDesign, so I thought it might be that, even though it was working fine until recently (I created the file on this MacBook and it was handling it fine). However, I tried to open it on my partner's much newer MacBook (2021), using the latest version of InDesign and its still crashing straight away.

I've trawled every forum post I can find, tried restarting everything, trashing preferences and caches, deleting recovery data, even running a script that was supposed to convert it to IDML without opening it (but it still crashed).
It's not a massive file so rebuilding it wouldn't take too long, but I'm just hoping that someone out there knows of a last option I can try that will mean I don't need to spend precious time building the file again. I know there are services you can pay for to examine or convert the file, but I'm not willing to do that.

Thanks in advance!