anything else for you to try. You have done what most here would suggest, disconnect from the mains, press and hold down the Power On button for 30 seconds.
When there is absolutely no response from the system, no BIOS, no POST, (Power On, Self Test), or no maker's logo if you do not see the POST messages, then I can't even offer you the Ubuntu LiveCD method we use to boot up into Ubuntu Linux OS from a CD to see if that sees the hard drive, and if so, to enable you to copy off your personal files and so on.
I take it you have no backups?
That power failure may have fried the PSU, power supply unit, but don't take my word for that as my technical knowledge is slim.
In fact I can offer a way forward to allow you to get to the files as I've just seen this is a Desktop.
Open the case, disconnect the hard drive and pull it out, then go get some external USB hard drive enclosure, or even a set of USB to IDE/SATA conversion cables as shown in Amazon.com, connect those to the hard drive, and plug in to the mains, then connect that to the USB port of any other computer you have, and see if the hard drive is still working. If so, you can use Windows Explorer to find your files and copy them off.
But other than that a dead system like this needs repair shop repair.
Sorry.
Mark