Seems like my angle grinder is just dead it won't switch on

Wow. This isn't much info to go on but let's try. I take it is not a brush-less motot

I also assume you know about electrics and have at least a multimeter

Before opening the grinder: Unplug the unt. Then with the multimeter set to read resistance (low to medium scale) connect leads (polarity doesn't matter) to the two prongs of the grinder's plug. Then make sure the to press the 'on/off' switch to the ON position. Now rapidly twist or spin the disc by hand. A reading will indicate if the grinder windings are OK. An analogue multimeter with pointer works best. Depending on the direction of twist, the meter will read either a quick positive or negative reading (or the analogue meter's needle will move either way).

In your case I assume no pointer movement or reading on a digital multimeter.

Now you'll have to open (dissasemble) the grinder.

Once open, first check for an obvious fault such as a disconnected cord supply wire.

If all looks OK, check continuity from the plug prongs to where is is screwed in in the grinder (follow the color of the wire). Check each screwed in lead at a time with your multimeter connected to a prong then first the one wire inside the grinder then the other. Then the same with the other prong. Also, while checking, physically twist the cable and see if you occasionally get a reading which means there is an intermittent connect/disconnect fault with the cables internal leads - a very good sign to replace it.

If both prongs show a zero reading (ie continuity) it means the supply cable is OK. If one prong shows no reading then that particular lead has opened inside the insulation where it is not possible to see. If this is the case, replace the power cord. This is often the case with a much used corded appliance and the break is most likely where the cord enters the device via a long rubber grommet. Lots of flexing takes place here while working.

All OK so far? Then check if you see a capacitor (a yellow, black or blue block with two leads) Unless it's obviously damaged or a lead is disconnected, you'll have to test it to establish if it's OK - or just replace it if the next tests are all OK. They're cheap.

Now check the state of the brushes normally found on such tools. One or both may be worn or broken. Make sure there's continuity from the supply wires to both the brushes with your multimeter and/or visually follow the wires.

While you're at it, closely inspect visible field and armature windings for obvious breaks or discoulering indicating overheating.

If the grinder was last used (just before it would not switch on again) on a very 'tough' job requiring for example a very lengthy grind or one needing excessive force, then a thermal overload protection fuse could be the culprit. This will open circuit (normally located in the field coils) so that no multimeter continuity is measured. This little fuse is wired in series with a field coil and is difficult to spot because it's usually shrink sleeved and inbedded in the coil wires. I have replaced some of these myself but it's a tricky job - the fiela coil wires are often hair thin.

If it's not the fuse you will be able to read continuity when measuring across the field windings (from brush connector to brus connector). If no continuity and the fuse is intact, suspect a possible break somewhere in a field wire - almost impossible to see as it may be hidden in the densely wound coils.

If OK it's time to disassemble further and remove the armature. With it removed, first chech the commutator copper segments for damags/excessive wear or shorts between any two of them. If OK, measure continuity between opposite segments. If no reading, suspect the armature winding have a discontinuity - also difficult to spot with the naked eye.

Good luck. Let me know what you find.