My XU2100 XTN series 2 Way radio is not working. Not receiving or sending transmissions to the other two radios. It is fully charged. It does not make an audible "beep" when you turn it on. Is this a speaker issue or a frequency issue?

Your radio is likely in need of repair. Flat rate repair for this model usually runs around $69. The fact it does not give you the initialization beep indicates it is more than a frequency problem. Then coupled with you do not have transmit or receive, this sounds like you have more of a problem than a bad speaker.

A few things to check before sending it for repair would be:
1) Swap the battery with a known good unit to see if your battery is bad/low and doesn't have enough power to function the radio fully.
2) Check your frequency and code to see if it matches your other units. This is in the upper right corner of the screen shortly after turning the radio on.
3) Check your mic opening in the grill of the radio to be certain it is not covered or free from debris.

If these any of these three items do not solve the problem, you should send your radio for repair.

Best regards.