Vacuum will not stay on, new bag in place and power to machine.

Is there a reset switch. Most vacuums have one some where near the bottom brush, to protect the vacuum from overload. If the vacuum tripped, the vacuum will not work until you've pressed the reset switch. If you can't find one, pls check manual.

http://www.managemylife.com/mmh/owner_manuals/6826/KENMORE-Vacuum-Upright-L0403208

The most probable problem is a clog in the hose.
First detach the hose from the vacuum and turn it on. If it runs without the hose, you're on the right track. Detach the hose from the wands and drop a coin in one end. Lift the end so the coin should drop through. If it doesn't, there's definitely a clog. Plug the hose into the exhaust port, place other end into front of vacuum, and turn it on. This usually clears it.
Also check the elbow at the power nozzle. Clogs here are usually visible, but you can hold the PN up to the light to check for a blockage.
If none of these take care of the problem, the entire vacuum needs to be taken to an authorized Aerus Electrolux shop for diagnosis and repair.

http://www.aerushome.com/storelocator/

First, turn dial on top of vacuum counter-clockwise so the smallest dot lines up with the arrow. See if it stays on. If not, detach hose and turn vacuum on. Place palm of hand over intake. If it turns off, it's possible that the tubes connecting to the CVA are clogged and simply need cleaned. This is most often caused by using "made to fit" Electrolux bags. Dust is sucked through the bags and into the motor compartment of the machine. All interior parts get covered in dust and need to be cleaned. If this is the cause, the vacuum is best cleaned and repaired at an authorized Aerus Electrolux store. If the vacuum shuts off, or won't turn on before placing hand over the intake, it's probable the control valve assembly is bad and needs replaced.

Another cause is an overheated motor due to clogged screen at back of bag well, full or clogged bag, dirty afterfilter, bad wiring/connections, clogged hose, clogged power head, or bad motor. It depends largely on the type and model of cleaner. Clogged wands are also a possibility, but unlikely.

Check and clean screen at back of bag well.

Replace bag. Make sure it's a genuine Electrolux bag made by Home Solutions.

Check and replace afterfilter if necessary. These should be replaced after every six bags.

Broken and worn wiring connections are often found in the hose ends due to abuse and normal wear and tear. You can check the continuity of the hose using a continuity tester or multi-tester. If a multi-tester, turn dial to one of the Ohm settings. Place one probe into one of the terminals on the end of the hose. This will be referred to as T1. Touch the other probe to each of the terminals/connections on the other end of the hose. These will be T3 and T4. One of them should read zero, the other should read infinity. Repeat this with the other terminal, which will be T2.

Drop a marble in one end of hose and let it roll through. If it doesn't roll through, the hose is clogged and needs to be cleared. Plug hose into the exhaust port of the vacuum, place other end in the in port. Turn vacuum on. This provides a blowing and sucking action which should clear the hose.
Detach hose from power nozzle (PN). Drop a marble into the wand end of PN. If it rolls through, it's clear. If not, there's probably a clog behind the brush where the intake opening is. You may be able to reach this through wand end with needle nose pliers, or either end with a knitting/crochet needle or a bent coat hanger.

If none of these "fixes" provide the answer to the problem, it should be taken to the nearest Aerus Electrolux store for diagnosis. Repairs or checks involving disassembly of the vacuum should always be done by an authorized Aerus Electrolux service technician.

The store nearest you can be found by following the instructions at the below listed link:
http://www.aerushome.com/storelocator/

Hi! I work at repairing Sebos, so can certainly help.  Most probably the cable is damaged, and the two most likely places for that to happen are where it enters the plug and where it enters the rewind mechanism. Before you even think about dismantling the machine to get at that end of things, though, you need to be 100% sure that power is reaching the machine.
I know you've tried a different socket, and that you've changed the fuse (by which I assume you mean the plug-top fuse, and therefore that you're probably in the UK like I am). Good first steps. Checking the integrity of the wire in the cable is a different matter, though. There are inexpensive devices you can buy to check for voltage through normal insulation, but I don't know how deep in to this you want to get...  you've got to be pretty keen (and competent) to think of changing the cable yourself. 
If you'd like to post a response, indicating how far you want to go yourself, I can help you get in to the machine if necessary.

The button I think you are talking about is the bag switch. It is located in the bottom right corner where you put the bag. If the bag does not cover it, the machine will not run.
Also, when the machine cuts off when the bag is full, you have to push the power switch off and back on to reset the full bag switch located in the switch control housing inside the machine.

The bag slips into the holder which should be attached to the machine. If you have taken this out by mistake and thrown it you'll have to contact Bosch to order a new bag holder.

Once you change the bag, be sure to turn the machine off and back on to clear the fault. If it is the full bag light that is on, and not the "?" light, and you have a new bag in place, then you probably have a bad control valve. I would suggest finding the closest Aerus (formerly Electrolux) dealer and having them change it. It shouldn't be too expensive. If you have the "?" light illuminated, the bag probably isn't pressing the actuator like it should. When placing the new bag into the machine, be sure the bag top presses the small button in the lower right hand corner. Good Luck!

first check to make sure there is a bag in the machine, if so make sure that its in securely, there is a pin switch in the bag door that wont allow the machine to turn on if there is no bag in it. If that's okay, then find the knob on the top of the machine ( in the middle of the canister ) and make sure its turned to the maximum, that is a sensitivity knob that can keep the machine from working ( in case it was clogged, but if its too sensitive it could think the machine is clogged when it really isn't ).

Either there is something wrong with your switch. Which it doesnt sound like it. Take it to your dealer or call another one it sounds like the control valve needs to be replaced. I am a dealer 1-866-966-9350.