My dell inspirion 15 isn't coming on

On most systems, the RAM is removeable, so you can either call Dell for a warranty support call, or before doing that, unplug the system, remove the base cover and disconnect the battery from the mainboard.  Hold the power button for 30 sec and remove and reinstall the memory modules. Reconnect the battery and replace the base cover.
If that doesn't get the system to power up, call support for repair.

Use the Support link at the top of this page.