The wallet appears to be encrypted or corrupted

Please see 2020 only.

Hexadecimal 20 is an ASCII spatial character. If the file does not contain anything other than 20, it does not contain useful data and cannot extract useful data†.

Maybe it’s encrypted?

Encrypted data generally appears to be a completely random sequence of hexadecimal numbers between 00 and FF. If the file contains nothing but 20 iterations, it is not encrypted.

The wallet.dat file is 180MB

Then I think you might not have seen all the part-timers to check it out all It is a hexadecimal number. Use a program or script to see if that 180 MB is a sequence of bytes other than a hexadecimal iteration. However, the chances of recovery seem small.

_{†You can encode a minority, e.g. 7458, as a count of bytes and repetition, but this is irrelevant in the context of recovery of a bitcoin wallet file}