If you have not, unplug the system, remove the base cover and disconnect the battery from the system board.  Hold the power button for 30 sec and then reconnect the battery and try powering up. If the system still does not power on, you're looking at a mainboard replacement -- at least $700 just for the part, and higher depending on the CPU and RAM installed, plus a minimum of $100 in labor to replace it, so the repair will be upward of $1K -- and most repairers offer only a 90-day repair warranty (parts-people.com will offer one year if they have the board, which they may not), so depending on what you paid for the system, it may wind up being a better idea to sell the failed system for parts and buy a new one with a warranty.  
Hi,     I purchased a used dell xps 13 9310 last summer, I woke up this morning to it completely dead, no charging status led, no response to the power button. I contacted customer support and they said they couldn't help me without an order number which I don't have. I am fine just paying for the repairs since I bought it used but am not sure how to setup the repair request. The site just asks for my service tag which says I have a warranty issue and need to contact customer care again.
repairing used laptop with no dell order number