sandman auto problem

Just wondering if any sandman users or former users have had this problem. Ive had mine for 5 years. While its plugged in it works perfectly. I only unplug it when i travel. When i plug it in after its been unplugged for some time ( more than just a few min) the display lights up, but the coviden icon does not appear, nor do any of the buttons function. Ive left it for up to 20 min to see if it would eventually kick in and it doesnt. I then unplug it, wait a few seconds and plug it back in and it starts like normal.
Just wondering if anyone else has had this happen?/ I know these are no longer serviced, but is this serious enough im going to have to get a new machine?.
thanks