Macbook pro shut itself off. Panic error message upon restart.

No, there is no free repair program. You will need to pay for the repair if the laptop is out of warranty.

The Kernel Panic mentions possible memory corruption which coincides with the volume hash mismatch errors you mentioned. Several people on these forums mentioned the volume hash mismatch error and Apple confirmed a memory failure requiring replacement of the Logic Board since the memory is integrated into the Logic Board. I believe you will need to have the Logic Board replaced.

You can try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the only useful diagnostic result is a failing test or having the diagnostic freeze the system during testing. You can also try running a longer more involved memory test by using a bootable Memtest86 USB stick. I have found customizing Memtest86's CPU settings to "Sequential" or "Round Robin" tend to reveal more memory issues than the default CPU setting. Many times Memtest86 will end up freezing instead of reporting a memory failure. To boot from USB you will first need to modify the laptop's security settings by using the Startup Security Utility. Again, a passing test does not mean the hardware is good, only that no issue was detected at that point in time.