nrf 52840 current measure for the beacon example.

Hi. I want to measure the current on the nrf 52840. I have downloaded the beacon example on the board and I want to measure current when the beacon is transmitting(LED 1 blinding). I followed the instruction about how to prepare the board. I have cut SB40. I have put the VEXT-nRF swtich(SW10) in the ON position. SW9 is in the VDD position as well. 
I'm providing external power supply through P21 (3.3 V).
The problem that I'm facing is, my board is not powering up with this setting. It only powers up when I put a jumper on P22. But If I do that, I can't measure current on P22, Since I can't connect my amp meter because of the jumper. As soon as I remove the jumper, the board loses power. Please suggest what can I do?