Help With Modded Xbox and Old HDD

I recently went to upgrade my old original Hard Drive with a new one, and went about trying to accomplish this using the Rocky5 softmod tool. I didn't realize my xbox 1.0 was already hard modded, so this caused issues once I installed it that made it no longer boot. I posted about it and managed to figure that out mostly, the Xbox is working now with a custom dash.

I have a new 2TB hard drive I formatted with FATXplorer and followed a guide on YT to get a dashboard loaded on it. So now, I'm trying to get a few things sorted and I'm not sure what to do.

First, it seems like the dashboard I got is UnleashX, when I thought I was getting XBMC4Gamers. I followed a guide on YT that had me go to a website called Hazeno that had C drive installs and it mentioned something about if you don't have Cerbios it'll always load UnleashX. I have no idea what bios I'm using or how to get it to use 4Gamers.. The mod chip in my system is apparently an "Ownmod" EPROM chip from ages ago.. XBMC4Gamers seems like the cleanest dashboard I'd like to use instead of UnleashX.

And second, the old HDD will not open with FATXplorer (and the xbox won't boot using the drive). I have the EEPROM backups from ConfigMagic to try and unlock the drive, but it will not even detect it. I've tried full restart of my PC with the drive turned on first, then loaded FATXplorer, waited up to 15 minutes for it to check and nothing. I've tried to use the HDD Security tools to unlock the drive, but it tells me each time it failed to check security details and wouldn't open. It has some old saves on it I would like to recover.