You may have had a voltage spike!
I'm late to the party here, but that blue component next to the fuse appears to be a varistor (MOV "Metal Oxide Varistor") which is a surge protection device. (AKA a Voltage Dependent Resistor or VDR) They work by reducing their resistance dramatically when a power spike happens. They are installed across the power lines, and normally have a very high resistance. If you had a spike, the varistor essentially shorts out the spike, and if it is a big enough surge, it will cause the fuse to blow. That's how they protect the circuit. Their response time is in micro- to milli-seconds.
In any case, the varistor may look fine but may be damaged internally and have a lower resistance, and current flowing through it. Voltage spikes will eventually kill them - the bigger the spikes the shorter they last.
If you still have access to the board, I recommend checking the resistance across the varistor. It should read as "open" or very high resistance, Mega-ohms or higher under normal conditions. The varistor should also feel cold or cool to the touch. If it is warm, that means it is carrying current and is likely damaged.
They are inexpensive to replace.