Please use only the Grace Digital Lithium Ion proprietary battery back in the Mondo+ in order to not void your warranty. We have been informed by numerous customers that the cheaper blue non-authorized lithium Ion battery sold mainly on Amazon may cause issues when used in the Mondo and Mondo Plus (+). Issues may include the radio often re-booting, freeze, or overheating or not powering on at all while connected to AC power. (We have attempted to contacted the non-authorized 3rd party manufacturer to tell them of the issue but they have not responded back.)
To purchase the official Mondo+ battery please go to the following link:
https://gracedigital.com/products/rechargeable-lithium-ion-battery-pack