Prompt Sony Z1 Fastboot File Recovery

Hey All!

I have a Sony Xperia Z1, which although advertised as waterproof, somehow got water damage after a day at the waterpark, even though all the flaps were perfectly closed and the phone even had a case that covered the whole back and sides of the phone.

After a few days of letting the phone dry out, now I'm able to connect it to my laptop, but only in fastboot mode as the phone won't boot up and I can't turn on USB Debugging to try and do something via ADB. Anyway, the bottom line is that I need to recover the files from my phone. I read about pulling files out through ADB, but I have no idea if it's possible to somehow acces the phone memory through Fastboot mode or at least switching to ADB using fastboot. The phone has insurance so I don't really care about the hardware, I just want my photos and files(which I realise I was an idiot for not backing up regularly).

Please help!

P.S. The phone isn't and has never been rooted.