So randomly the other day when I went to manually restart my toshiba satellite due to a synaptics failure/crash, my computer would not start at all. Long story short, after taking it apart and reading multiple threads I came across one which mentioned the solder joint being cold and references to cooking the motherboard/ 'blanket trick'.
Since the computer was already apart I took a hair dryer to it and baked the motherboard. Specifically in the lower middle part of the motherboard, when applying heat towards that area the computer boots up fine. I left it to cool and after awhile it starts to fail again.

My question is does my motherboard need to be replaced or could I just reheat the joints permanently with some kind of tool? Is this common for a 4 year old computer? Basically what are my options at this point, and if you're up for it could you explain why is this happening?