Do a CMOS Memory (BIOS) reset.  See if that helps. Power off PC, disconnect the AC power cord to the power supply.  Press the power button for 10 seconds to drain any residual power. Open the case and locate the 2032 coin cell battery on the motherboard.  Remove the battery for at least 5 minutes.. Reinstall, connect the AC power and power on PC. Another possibility the motherboard has a hardware problem.
xps 87002tb hdd 256 gb msata  windows 10 Tl;dr old mobo fried, installed new motherboard, now the computer won’t boot, need advice on how to troubleshoot. My dads computer stopped turning on a bit ago and I took a look at it and found the motherboard had fried. I bought a used one on eBay and got everything replaced and now the computer turns on, but it tells me the boot device can’t be found. I looked around in the bios and it’s able to correctly identify the hdd and the msata. I booted from ubuntu via a usb and was able to back up all the user files on the 2tb hdd so it doesn’t appear at first glance the hdds are corrupted, but I haven’t run any diagnostics on them yet.  it also seems that Dell’s may have hardware/software configs that need to be exact like outlined here: [URL] I’m also not clear on the boot setup with the ssd and the hdd and if it should be legacy or eufi or raid  it seems like the windows and boot files are on the hdd, so I’m assuming the ssd was used as a cache, but I’m not positive. I had a win 10 usb installer that was used for another pc that I plugged in and booted from to try and repair, but it didn’t work.it gave up after 2 seconds. Does any one know what the proper steps are that I should take to troubleshoot and get windows booting again? I have set the bios to default at the moment which is on legacy. 
XPS 8700, new motherboard, no boot device found