Simple fuse box fix?
There are NO fuses that prevent the car from running. Since you have only "some power" and I'm guessing?
no headlights? park tail dome?
And it won't crank?
But you DO have power at some point in the fuse panel
THIS IS LIKELY a failed "welded splice" up under the dash in the ammeter black wire from what you said
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Start my making absolutely sure the battery connections are good
Test for voltage.......quick way is with a test lamp for now.
Check at starter relay "the big stud."
From there ALL MAIN POWER feeds in through the bulkhead through the fuse link. So follow that short wire to the bulkhead connector and check it and wiggle it.
Now jump over to the alternator main output stud.........the black nut connection. You have power there?
You can download service manuals and wiring diagrams at MyMopar.com
ALSO READ this article:
Catalog
In that article, pay attention to this simplified diagram, which shows in a nutshell the main power distribution:
Follow along the diagram above. I am going from pos to neg which is AGAINST current flow, for "function"
From the battery, power goes to the "big stud" on the starter relay
From there the "fusible link" hooks to a short red wire and goes through the bulkhead connector AND DIRECTLY TO the ammeter (RED)
Through the ammeter, changes to BLACK and goes to the WELDED SPLICE
The splice is up under the dash in that BLACK ammeter wire, you will have to untape part of the harness to inspect it.
FROM THAT SPLICE branches off UNFUSED!!! to feed (depending on year/ model)
Feeds to headlight switch for HEADLIGHT power ONLY (not tail, park or cluster)
Feeds to IGNITION SWITCH
Feeds to fuse panel HOT BUSS
ALSO from that splice the BLACK continues on BACK through the bulkhead connector and ends up at the alternator main output stud
ALSO BE CAREFUL with your tests. You may have "wiggled" a bad connection and lead you down the wrong path
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TO REPEAT........
If you do not have headlights or starter/ ignition/ engine, the problem IS NOT IN the fuse panel. NONE of those devices are fused