Dear,

There's a common fault with Dell Latitdue E5 and E7 series, not sure you have a fix for that, which is it doesn't power unless you disconnect the internal battery or CMOS battery then reconnect them, you can check this link as it says engineering defect

https://www.dell.com/community/Latitude/E5xxx-and-E7xxx-No-Power-Dead-Possible-Engineering-Defect/m-p/7300303#M12411