Start button broken

the contacts in switch are bilt up with carbon!if you're handy try taking it apart And cleaning the contacts.or buy a new one

You will need to pull the grinder apart & clean it out. Most likely cause of the grinder blocking up is a leak somewhere inside the machine dampening the grounds as they exit the grinder. They bind up, won't fall out and there is your blockage. You will need to find and fix the leak, there are many, many places for the leak to be, it's a job for a Krups Service Agent. I have outer housings with cutouts in them so I can run them and look inside at the same time to find those troublesome leaks.

the wire to the circuit broad switch maybe broken

Unable to find any parts supplier who offered a replacement blade for the CBG5 SmartGrind Coffee grinder, the broken plastic center spindle was reconstructed around the attachment nut, and an epoxy cement was poured around the nut and over the center of the blade.
This solution has worked in testing the blade on the grinder, but how long it will hold up has not yet been determined.
T.B.

check the mechanism is not blocked, undo the screws at the front. Remove the baseplate, there is a 1.25 a fuse attached to it under a black plastic cover. If neither of these thing work, is there a burning smell?
Could be the motor. I imagine it is just the fuse.

The grinder parts have to be in place and the lid closed or it will not work. The plastic cover to the grinder twists to the left which engages a small switch. Hope this helps!

Just adding to dhelkamp's instructions (which helped me immensely!).

The front quantity knob kan be pulled right out - it's held in place by friction only.

The side knob has 3 latches holding it in place. Releasing 2 is sufficient. Use 2 small flat screwdrivers.

As for the assembly, there are 4 latches in the inner assembly holding it in place. The location of these latches can be seen by looking at the edge of the outer shell. The front latches are just behind the holes for the rubber feet, and the rear latches are just in front of the rear holes. Use a flat screwdriver to release one of the front latches, while pressing down on the outer shell - it should give way 1-2 mm. Repeat on each of the other 3 latches, whilst keeping pressure on the outer shell. The cover should easily slide off the grinder assembly. Beware of getting pinched!

I think I solved this (I had the same problem). Upon removing the top, I found that the solenoid that moves the trap-door for the grounds was loose, and the mount where it attaches to the plastic frame was broken. Basically, the little plastic fin that should hold the lower flange of the solenoid was sheared off. That left the solenoid free to move, and made the action necessary to move the dispenser trap door impossible. Instead of doing it's thwok, thwok thwok, it would just hum.
It looked like there was no easy way to replace that part of the plastic mount, so I have epoxied and zip-tied the solenoid into place. It seemed to fix the problem.
-tony

Open the grinder by removing both knobs.
The front knob is held in place by friction. Use two flat head screwdrivers to pry it off.
The side knob is held in by tabs you have to push. Pry forward to expose the tab, and use another screwdriver to press the tab, and use the other screwdriver to press the tab on the other side.
Now look at the bottom of the grinder. There are four tabs on the outer shell, use screwdriver s to pry the tabs to separate the bottom of the grinder from the shell, and pull off the shell. Your fuse should be attached to the motor wiring coil.

My grinder went from bad to worse and finally stopped grinding (with the motor still buzzing but absolutely no grinding). Knowing I had to do something or throw it away, I pulled the clear plastic bean reservoir upward and separated it from the grinder body. I looked down the hole where beans go down to the grinder and found packed coffee ground blocking the hole. I cleaned the whole thing, put the reservoir back, and my grinder now works like new :-)