Hi I`m Jack a tech. with 40 years repairing audio equipment and i won`t even ask you the model number of that amp .
Installing larger fuse is definitely not gonna make the problem go away and it doesn`t mater if there are no speakers .
From what you described here you have blown output transistors hence the protect mode and a shorted power supply hence that blowing fuse.
Sorry but this amp is very sick and needs a qualified doctor at this point and again if it is worth the cost of repair
Take it to a shop for an estimate , most of them will do it for free or low cost.
That is my best advice .
Sorry for the bad news but i`d rather be straight with you .