After you file

I have been trying to file a 1040x for my step son this week and its slightly confusing. My lines 17 and 18 are the same....I used the tax table for lines 6. On his first filing the W2 he recorded has 36.50 fed withheld and his refund was 37 so he got it all back? Now on the new W2 he needs to amend there is no federal withheld at all. 

 

Line 1806.004907.315713.31
Line 212200.00-12200.00
Line 311394.004907.316486.69
Line 4b---
Line 511394.004907.316486.69
Line 6 (Tax Table 2019)1171.00493.001664.00
Line 81171.00493.001664.00
Line 111171.00493.001664.00
Line 1237037.00
line 17  37.00
Line 18  37.00
Line 19  0.00
Line 20  1664.00

 

So does this mean he owes taxes? I can only assume because he didn't withhold anything on his W2.