I got a couple cheap lights with 3 modes (low, high, strobe) and I would like to remove all but the high mode. I read about the pencil lead trick to short the capacitor but it did not work for me. I tried putting solder across the capacitor but then the light would not turn on at all. Luckily it still works after I removed the solder. What will happen if i remove the capacitor altogether? Are there any other things I can try? Here is a schematic CX2859 Datasheet - Multi Cell LED Driver, SOT-23 ( Pinout ) and a picture of the circuit board Imgur: The magic of the Internet Thanks
How about remove the cap
You can also try adding a resistor on the capacitor
You can consider your self lucky ! Shorting the capacitor .., you just put your battery in parallel on the resistor (R300) , in the schematic this has the value of about 330 ohms so, only a current of about 12 mA .., what if that resistor was only few ohms ? A lot of smoke and possible a damaged battery !!!
On this particular driver you can NOT do " one mode only" , because the 3 modes are factory set in the internal memory (sometimes you'll find the same circuit with 5 modes ).
The only trick that could be done is to make it start in " high" every time , from off , by soldering ,in parallel on the capacitor , a resistance , 47K...100Kohms !
Good luck !
i knew i was taking a chance when i did that. thank you for the information 
i will try your suggestion