Are the play buttons on your Denon Prime 4 giving you trouble? Need to replace the Play/Pause button plastic shell?  Seems to be a pretty common issue.  I've got one left in stock and it can take months to get more.  If your Prime 4 problems run deeper and you're in need of help, feel free to reach out.  I've been pro audio doing tech work professionally for roughly 25 years. I've had a Prime 4 on the bench here a couple of times before and am familiar with it's guts. 
 
Denon Prime 4 Play Pause Button Replacement  - PT11106683