Fuse & Starting problem

What is your question?

Here rescently when i had the main fuse loom bypassed the repair shop used about 3 sealed fuse links by the battery where the fuse box comes out from the firewall and ! of them had gotten corroded from being next to the battery . So i replaced with a flip top fuseable link wire rated up to 30A using a 30A fuse in it , But every once in awhile it wont start not even dashboard lights come on at all everything is totally dead so i will have to change fuses out with another one thing is the fuse dont blow out. Im wondering is the 30A im using the reason its doing this? Cause i dont know what the other 3 wires that i mentioned even have fuses in them or what. What could the major problem be causing this ?