4 Amber lights is an indication of a RAM error. Try removing and reseating the RAM. If that does not help, make sure the RAM modules are in the correct slots. Try removing the CMOS battery and after 15 minutes reinstall it. If none of that helps restart the system and start tapping F12 right away. Run full diagnostics and watch for any RAM errors. Also one tip, if you reinstall Windows, unplug the HDD. Windows can have a habit of installing some of the files on the HDD instead of all files on the main SSD.
Recently I replaced the factory HDD in my XPS 8930 with two WD drives, on is a M.2 pcie drive (500gb), and the other is a 2TB HDD drive, I plugged both in and booted the computer up and it seemed to work normal, and I was able to normally reinstall windows, then it froze and I shut it down, now when I go to power the machine back on, the power LED flashes orange/amber four times every three or so seconds. I've read that it could be because something is plugged in wrong, or not at all. But everything appears fine. I've unplugged everything that I could think of from the inside of the machine, swapped the SATA cable port several times and nothing.  I'm starting to run out of ideas on what might be the issue, someone from Dell support said that it could be the hard drives themselves, but even with both drives unplugged, it still flashes orange four times. 
XPS 8930 HDD issues