Do you have any pullup/pulldown on the reed switch pin? If the reed switch is normally closed that'd obviously cause power draw, but if it's normally open and there's no pullup then any electrical noise on the pin (or any other pins set as inputs) could cause activity inside the nRF52 which draws more power.
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Do you have up to date firmware?
Do you have any pullup/pulldown on the reed switch pin? If the reed switch is normally closed that'd obviously cause power draw, but if it's normally open and there's no pullup then any electrical noise on the pin (or any other pins set as inputs) could cause activity inside the nRF52 which draws more power.
... but also if you look at http://www.espruino.com/Puck.js#power-consumption unfortunately just adding a watch to a pin to check its state can add around 10uA of power consumption.