Hi @wakjal ,
It may be an intermittent problem with the Power button.
Here’s the [https://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_inspiron_laptop/inspiron-11-3148-laptop_owner%27s%20manual_en-us.pdf|owner manual] for the laptop.
Go to p.31 to view the necessary pre-requisite steps and then the procedure to remove/replace the ''Power and Volume buttons board''.
Once the board has been disconnected from the motherboard use an Ohmmeter to test if the Power button contacts are making OK ''everytime'' that the button is operated and if not then the [https://www.ebay.com/itm/Power-Button-Dell-Inspiron-11-3000-OEM-Genuine-450-06Q04-0001-Volume-board-/183655443694|board] will have to be replaced, (supplier example only to show cost of board).
There are other suppliers online that may suit you better. Just search for ''450.06Q04.0001'' to get results.