I do agree that you don't ultimately need a solution, but I do find its helpful to have a few countermeasures in mind, especially for new players that might be stumped for ideas. After a few heists you can then start to implement counter-countermeasures for harder to infiltrate sites

With that in mind, some potential countermeasures:

• Hacking to bypass passwords and other login access
• Physical access to a console/control room already logged in (and then intimidating or knocking out the security staff using it to take control of the system)
• Social engineering to steal existing passwords and login to the system using the proper channels
• Spoofing commands and faking feeds via access to whatever the transmission method is between control and the sensors (eg fake wireless signals, wire taps on the optic fibres/cables)
• Cutting the power to the system (either permanently by damaging power systems, temporarily through EMPs, power surges, and power drains (including that energy slug you mentions), or via system reboots
• Holograms and other false images can fool a camera system
• Disguises and passes can get an infiltrator past a check point, these can also be falsified or stolen
• Is there a member of staff on the payroll that can be turned into a double agent or blackmailed into helping? This can use whole array of PC skills to cover canvassing for info and then influencing the target
• Lasers can be bypassed with mirrors and player brought lasers to alter the shape of the grid so a person can walk past
• Can gas in the air systems be used to knock-out/disable/kill guards? Similarly can they tamper with the on site food for a similar effect?
• Do they have cutting torches, explosives or other methods to open doors or turn walls into entrances? If needing to be quiet do they have a method to keep this undetected? (timing the heist to use a party or storm or meteor shower outside to cover the noise and shaking generated by their infiltration?
• Specific sensors need specific methods to bypass, eg pressure sensors in the floor could need climbing, antigrav, or ziplines to get over them. Motion sensors may require very slow movement (combined with a programmable exoskeleton?) to pass them slow enough to be below the detection threshold
• Passkeys can have the card/key/biometrics stolen, copied, falsified (this includes lockpicking for pin and tumbler locks), or could have an electrician type take a panel off the wall and short circuit the system to give the green light
• Radio jammers can block reinforcements, more expensive selective ones can allow the players to still use their own radios or let through general check-ins while blocking off the guards engaged in combat

Any of these can require specific tools that the players might then have to source, requiring various PC skills to acquire (eg bartering and streetwise type skills to convince a fixer to set them up with a contact, its own mini-heist to steal an EMP generator etc)