Here is an IFIXIT guide that will walk you through the removal and replacement of the motherboard. Motherboard R&R
What you need to do is FIND a replacement USB A jack... I couldn't find one for sale.
Suggestions... get your hands on a non-functioning one "for parts only" hopefully cheap, or find another defunct Dell with the same jack to steal the part from. That's what I did to replace a bad one on a Toshiba Qosmio that has since passed away (all the plastic parts eventually got too old and brittle to keep it working.}
Once you find the replacement de-solder the old one, install the new one and put it all back together.
There are lot of videos on how to do the necessary soldering if you aren't up on that easily found on-line.
Good Luck.
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