This is a situation where maintenance will choose the fastest way to get people off of the ride. If all trains were stacked behind the station (none stopped out on the course), then, usually, the fault is relatively minor because the system allowed all the trains to return to the station. But since there is a fault registered, dispatch will now be prohibited and the operations team will have to call maintenance.
In most parks, operations cannot initiate an evacuation- they will only assist. So the 10-15 minute wait time that was described probably involved operations trying to recover the ride themselves, then calling the ride in, maintenance responds, maintenance does a quick assessment of the situation. As I mentioned above, the fault was probably minor, so maintenance was probably able to clear the fault and cycle empty to get everyone off.
When an evac takes place, in some parks, maintenance will discuss with operations the need to evacuate. From there, the ride will be powered down and anyone involved will need to place an individual lock over the power key (or where ever the lockout is). Then gather any equipment needed. In Bolts case- a battery box. Then they will then proceed to go out to do the evac. If they did evacuate, in a NORMAL situation, the 2nd station would be evac'd first and then the transfer. But with the rain, I would imagine/ hope that operations (with maint. help) would opt to evac the transfer train first. Each row would be unlocked individually and riders would be escorted to the exit.
TL;DR: The 10-15 minutes that a ride is down is usually: 1-2 minutes of operations troubleshooting.... 1 minute to call the ride down.... 5 minutes (depending where maintenance is in the park and if the ride is accessible via service roads).... 1 minute quick analysis to what happened... 1 minute of ride resetting... 3-5 minutes to cycle down the trains.
If they evac'd... it would probably be: 1-2 minutes of operations troubleshooting.... 1 minute to call the ride down.... 5 minutes (depending where maintenance is in the park and if the ride is accessible via service roads).... 1 minute quick analysis to what happened... 1 minute of communicating to the ops department an evac will take place... 2-3 minutes to follow proper lock out procedures... 1-5 minutes to gather equipment and walk to the train (depends if the train is out on the course somewhere)... probably 30 seconds to 2 minutes per row. (different per ride). Then another 1-10 minutes of escorting to the exit (again depends on where the train is).
Sometimes it is faster to reset and cycle down than it is to evacuate the train.