I noticed you haven't tried adb. Install android tools and look for a binary specifically called fastboot. Boot into fastboot mode and connect the phone. Run fastboot devices and look if it lists. If it does you have some options.
As for data, is your data backed up / synced somewhere? Or do you need data recovery?

If unlocked, sideloading would be a way to boot a live image or a custom recovery. There should be a way to reflash the complete phone to factory defaults from an image you can download.
But it sounds looks your storage got corrupted somehow which is not a reason to trust the hardware after it works again.