How should I handle an OS drive that seems corrupted?

First, work out which physical drive actually held Windows. With several SSDs and hard drives connected, the drive that looks corrupted may not be the OS drive, and a healthy status report does not prove the filesystem or partition layout is usable.

If any data matters, avoid formatting, wiping tools, or repeated repair attempts until you have a backup or recovery plan. For a clean reinstall, disconnect the other drives temporarily, then install Windows to the replacement drive. That reduces the chance of selecting the wrong disk or having boot files placed on another drive.

A SATA SSD is a perfectly reasonable choice for an OS drive here. You do not need to use the M.2 slot just because one is available. A PCIe-to-M.2 adapter can also work in some systems, but compatibility and boot support depend on the motherboard, so check its documentation before buying one.

If you replace the existing M.2 drive, keep it untouched for now and connect it later with a suitable enclosure or adapter to see whether its files can be read. If it is actually the failing drive, connecting it again can carry some risk, so prioritize copying important files rather than using it as a permanent extra drive.

That “full” message by itself does not tell you the drive is physically dead. The installer may be seeing existing partitions or an unexpected layout. Check the disk and partition sizes carefully, and do not delete anything until you are certain you have identified the right disk and have saved anything you want to keep.

For a fresh install, the safer simple route is a new SSD, with the other drives disconnected during setup. Once Windows boots from the new drive, reconnect the old drives and copy files over. If the installer still cannot erase the old disk, stop there rather than trying random wiping utilities.