2009 SAAB 9-3 WONT START

my 2009 Saab 9-3 wont start, I bought a new battery about a month ago and had my winter tires put on a week ago.
I can use my key fob to unlock the car but I cannot push down on the break and when I try to start it, all you can hear is that clicking noise.
I had it boosted and drove it on the highway for about an hour and straight to the mechanic, but the mechanics got it started no problem and couldn’t find anything wrong with it but did mention the engine is that of a Chevy Cavalier.
The problem is inconsistent so I’m not sure what good it will do to take it to another mechanic.
Any knowledgeable input would be greatly appreciated.

[Kabuto]

I have the exact same issue my dude but your cluster is tweaking because of weak battery. Mine wouldn't start with starter bypass as well.

[dravenrosenbaugh]

Depending on where you got the battery it could already be bad cause it sat awhile. Try returing it for an exchange or either a refund.

[Farmer]

Hi i have a saab 93 2006 vector, i took the battery out to charge for
about a week when i put it back in the key will turn everything works
but nothing when i go to start car but worked perfectly before i took
battery out i took the starter relay out and put 2 wires in the holes
motor turned over but wouldn't start i tried again with key but nothing
just silent when i go to start any help appreciated.