Rebbot and select proper boot device error

almost sounds as if one of the cables on the hard drive isn't connected properly.

That notice is usually an indication of hard drive failure or corrupted OS files. There are a few avenues of approach available here... 1) reinstall OS - hopefully you have disks and your backup is not partioned on the hard drive. That may not work depending on how messed up the hard drive is and you will lose any data on the disk. 2) Replace hard drive - I would suggest putting an SSD in it's place - again, restore disks are needed to do that. The advantage there, not to mention the super-speed of an SSD, is that you may be able to recover data from the damaged hard drive. 3) The last possibility is to attempt a repair of the hard drive. You will first need to make a bootable CD (or DVD) and include some kind of repair software - there are free versions available but I am not familiar with them enough to recommend any specific program. You then boot from the CD into DOS and follow the instructions to attempt repair. Again, data loss may be a concern.
On a side note, even if you need to purchase a new hard drive (SSD) and operating system (if you do not have recovery disks), it'll probably be a bit less expensive than renewing your contract with Dell
Hope it helps

on another pc make a hirem boot cd or usb stick. run anti virus scan and then a malware bytes scan. use hd tune or another program read the smart data info on your hard drive to see if there any warnings. then run hard drive vendor test tools that are on the hirem boot cd. see if they pass or fail.

Press F2 to go into the BIOS and go to the Boot Device Priority. Change it so that your HDD is first in the list and then the CD/DVD drive and so on. Also be sure you don't have a printer plugged in via USB as if it has a card reader on the printer it could be causing the system to get confused and it be trying to boot to the card reader (I've actually seen other DELLs do this).