battery power problem

by powering the mkrzero, mkr1010 and mkrfox1200 boards with a 3.7v (3.0Ah) lipo battery, the ON LED is lightly powered. in the data sheet it is specified that the led on is off when we use the battery. This does not happen. this compromises the use of boards in low-power applications.
Could anyone check this out?

thanks and happy new year

How is the battery Connected?