Datasheet

will start to blink at a frequency of about 2Hz. This flashing is caused by the following conditions
maintained for a long time (from 20 to 70 minutes): - No battery is connected to JST connector. -
Overdischarged/damaged battery is connected. It can't be recharged. - A fully charged battery is put
through another unnecessary charging cycle. This is done disconnecting and reconnecting either VIN or
the battery itself while VIN is connected.
Onboard LED
On MKR ZERO the onboard LED is connected to a dedicated pin (32) and not to 13 as on other boards. It
is so suggested to use the LED_BUILTIN define .
(*) Note : DO NOT CONNECT to the male JST connector present on the board anything else than a
Li-Po battery whose characteristics are compliant with those indicated above. Please DO NOT
POWER VIN with more than 5V.