(1) Try to turn in on while connected to an outlet. (2) Hold the power button for ~15 seconds, let go for a few more, then press it again. (3) If none of the above work, check this link to diagnose possible errors beyond the battery. (4) https://www.dell.com/support/kbdoc/en-us/000152770/portable-led-diagnostic-code-information?lang=en