Teenage Engineering OP-Z battery

  OP-Z, the battery specifications are:

• Li-Ion 740mAh
• 3.7V-740mAh-2.74Wh
• 6 hour battery life
• 1 year stand-by time
• user replaceable

The battery is hard to find.

If  The OP z hasnt been used for a while it may just have to be woken up.

Apparently this is common with Li-ion batteries 

 

From the support pages this worked:

 

 

• connect OP-Z to a computer or usb charger, using the usb-c cable, and power it on.
• while still connected through usb-c, turn the unit over, loosen the four yellow screws and remove the back panel.
• remove the battery from the OP-Z.
• press the screen index button on OP-Z.
  a red led will light up, confirming no battery is present. this will reset the battery indicator.
• Leave the OP-Z connected to the USB cable/power
  
• turn OP-Z off and reinsert the battery back in the unit.
• Leave the OP-Z connected to the USB cable & power
• Let it charge up to at least 1 hour
• Disconnect the USB cable
  
• turn OP-Z on and you should be good to go. 
• seal the back panel and continue to charge the battery.