You could try pulling the CMOS battery and leave it out for at least 15 minutes ( I like to go 30 minutes myself) then either reinstall that battery or even replace it with a new battery. The process is available on this support page and the battery specified on that page is a CR2032.
Hi I used the Support Assistant to run through some updates of which it recommended a BIOS update as Urgent. Applied this update and then it rebooted and then failed to start back up after 30 mins or so. Have tried to use F12 (will not kick in) and the BIOS Update loaded on a USB stick however it will now not boot (cycles round failing on a Firmware Update) on ME Firmware EndUpdate Failed Error: 0x00000162.Reboots and then say starting recovery mode message (but no ability to get into the BIOS to allow a USB Boot). Consistently now rebooting constantly as it will not allow me to boot from the USB stick.  Any ideas welcome? Nick
Dell Inspiron 3881 - BIOS Update Failed (Unable to boot up)