I amended my 2019 federal and state tax returns and expected a refund of over $2,000 form the feds but receceived less than $200. No explanation was provided. What steps should I take to find out why there was a difference. My full state refund was made.

You will eventually get a letter from the IRS with an explanation. But $2,000 v. $200 sounds suspiciously like a decimal point error, so carefully review both your 1040 and 1040-X  filings.

But it's also possible that the IRS did an offset for back taxes, child support, etc.  If so, you'll get a letter.

if your revised 1040 was wrong, your 1040-X will be wrong also.

IRS made corrections.

Go back and double check your work that you submitted.