Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
This often happens (if I am judging correctly as to the problem your device has) when an old device becomes heat-sensitive in the rarer way - so that it won't work unless it is fully warmed up.
In that case, when first turned On, nothing seems to happen with the device - but 10 or 15 minutes of being On later, when well warmed-up, it starts to function.
Is there any sign of the device doing anything, until minutes after being turned On, it suddenly seems to be starting to work? if so, then my guess is correct.
Heat-sensitivity like this, in an electronic device, esp. one that has been in-use for years, means one thing simply: it's nearly completely broken, it will need a not-inexpensive repair to get it fully working again.
So ultimately, the answer is: there is no easy fix for this problem. It will need either repair (and worse, repair of some expensiveness) or replacement.