Try using Command + Option + R to see if you can access Internet Recovery Mode for the online macOS installer.
Command + R may not work if the internal drive is bad (or macOS has been erased or damaged) since that key combination will try to boot from the local recovery partition on the internal drive.
If you still cannot boot when using Command + Option + R, then do you have access to another working Mac from 2008 to 2021?
FYI, please take note of the exact keys listed and when replying since it can make a huge difference in success & failure, plus for us knowing what you are doing since I don't know what "Cmnd+R+P" indicates except maybe you were trying a PRAM Reset and forgot the Option key when you replied?
Also, make sure to press these special startup keys immediately after hearing the startup chime. If you wait too long, then the keys won't register as a boot option. Since a Mac Mini 2014 can boot quickly, more than a second delay could cause it to miss the special key press. Sometimes holding the keys before the startup chime will cause them not to be recognized either...it varies for some Macs.
Did you try running the Apple Diagnostics?