New Mac mini won't turn on

Since your new Mac mini (M5 Pro, 2026) worked normally yesterday, first rule out a power problem.

Disconnect the Mac mini from power and disconnect all accessories. 

Check that the power cord is firmly connected at both ends and that the electrical outlet is working. 

Wait 30 seconds, then reconnect the Mac mini directly to the outlet. 

Apple specifically recommends this 30-second power disconnection for the current Mac mini. (Apple Support)

Press the power button on the bottom of the Mac mini. 

If it does not respond, press and hold the power button for about 10 seconds, release it, and then press it once normally. (Apple Support)

If there is still no response, try another known-working outlet and, if available, another compatible power cable. 

Check the front status indicator light for any sign that the Mac has started. 

A solid white light indicates that the Mac is on or asleep; no light means it is off. (Apple Support)

If the Mac mini remains completely unresponsive, it may require service. 

Apple's current repair manual specifically includes a “No power” troubleshooting procedure for the M5 Pro Mac mini. 

Because this is a new Mac, I would not open it or attempt hardware repairs yourself. (Apple Support)

There is no need to perform an SMC reset; that procedure is for Intel-based Macs and does not apply to Apple-silicon Macs.

Apple's relevant instructions are Take a tour of Mac mini, If your Mac doesn't turn on, Turn on a Mac mini without pressing its power button, and Mac mini (M6 or M5 Pro) Repair Manual.

If the power source has been checked as OK and the power button does noting then I would return to seller. You have 14days to return the unit if purchased from Apple.