How long should an unused Mac for a couple hrs take to turn on when plugged into power

Macpowering wrote:

How long should a dead Mac (for a couple years) take to fire up. 2017 model Mac Pro

A question would be what were the issues prior to being dead for two years...?

If your Mac doesn't turn on

https://support.apple.com/en-us/HT204267

While plugged in you can try—

—resetting the SMC https://support.apple.com/en-us/HT201295

—resetting NVRAM/PRAM http://support.apple.com/kb/ht1379

(get at least two-three rounds of the chimes when holding the NRAM Reset)

I assume you mean on battery power.

Likely for an infinite period of time as the battery has likely discharged to the extent of reversing its polarity. Batteries need to be exercised to maintain their health over time. They do decline of course, usually steadily over a period of years, but sitting idle for two years is a death sentence most of the time.