Woke up to a dead truck?

When it’s that far gone, twisting the nut will only turn the entire bolt, the square bolt head will turn and probably strip it’s retainer things. If you’re lucky the bolt will snap. I put vice grips on the square bolt head and try twisting the nut. 10mm might not fit anymore. Maybe 9, or whatever you have that fits tight.

Once you accomplish getting it off, remove the battery. Find a container that the entire terminal end will fit into. A water bottle with the top cut off, a empty margarine tub, whatever. Fill it with coke, walk away. Later disassemble everything you can on the terminal, scrape any stuck on acid, dunk it again and leave it. Later it should look acid free, coke does an amazing job, then decide what needs replacing.

Spray on protector is good, definitely better than nothing. I tried the noco felt pads, they worked excellent. Noco also makes a good spray on cleaner.

If you have a battery charger, hook it up while you mess with the terminals.

Before you reassemble, brush the terminals and posts with a battery brush. Even if you’re using new terminals or battery, brush them. If you use spray on protector, use it after it’s all put back together, not before.

Ez red makes good battery brushes, I use the ones that attach to an impact driver. The hand twist ones work fine too.

After reassembled, look at the battery once in awhile. Stay ahead of letting that white crap from building up. Terminals and posts get oxidized and and need to be brushed. If not, plan on getting stranded.

 

$14 E-Z Red (505BTSSHQD) Battery Brush

https://www.amazon.com/gp/product/B00I3GNM62?ie=UTF8

$14 EZ Red EZR-BK534QD 0.75 in. Power Drill Wire Brush

https://www.amazon.com/gp/product/B07FJN51J9?ie=UTF8

$8 NOCO NCP2 MC303 Oil-Based Battery Terminal Protectors, Anti-Corrosion Washers, and Battery Corrosion Pads (Pack of 2)

https://www.amazon.com/gp/product/B001DKUTR0?ie=UTF8

$13 NOCO E404 12.25 Oz Battery Terminal Cleaner Spray and Corrosion Cleaner with Acid Detector

https://www.amazon.com/NOCO-E404S-B...aea7edf3f67&pd_rd_wg=t1FHg&pd_rd_i=B002MGTNX0

 

when i clean my engine bay, i soak everything with tire foam cleaner/shine.

then i pressure wash keeping the tip a few feet away.

i don't open anything or do anything else.

been doing it this way to detail cars for over 20 years. never had a problem on an ignition coil modern car. (old cars with a bad seal on the distributor need to get compressed air to dry)

just clean the terminals, install the felt washers around them, smear some dielectric grease or Vaseline (it works just fine) then tighten the cables to the terminals to whatever torque specs the fasteners can handle without stripping.

 

In the past in a pinch on terribly corroded terms, pour a bit of white vinegar on that bad boy. It'll loosen right up. The + lug, same on my truck and the 08 Camry, is a bugger to clean due to design.
Keep them cleaned like once a year with a good brush and application of silicone grease.