New to Arduino - I have issues with Serial Monitor and it's output by scanner

Projects Programming
3

Welcome to the community.

88
48
48
48
75
54
65
84
74
82
19

This is not HEX(hexadecimal). This is DEC(decimal).

Refer to ascii table to understand the differences.

You are getting the correct value of 'X000K6ATJR' but it is represented in DECIMAL notation.

change this

Serial.println( key );

to this

Serial.print( (char)key );

Next time, post your code in code tags. Read the post suggested by @TomGeorge.