If you have another computer available, you can use it to check that the USB drive is bootable on it, if possible. Make sure that the drive is plugged in before power on the computer. Press the key (F12 / F2 on a Dell) repeatedly while power on the computer to get to the boot menu.

Possibly useful links:

https://www.dell.com/community/Inspi...7503114/page/2
check the last post on page 2 of this link.

https://recoverit.wondershare.com/us...-from-usb.html

https://askubuntu.com/questions/7269...-dell-inspiron