Startup Humane Inc told users to stop using the charging case of its Ai Pin device because of a fire risk, adding further uncertainty to the product’s rocky rollout.

The company told owners of the device that it identified a “quality issue” with the battery inside of the case, which lets users charge their Ai Pins on the go. Humane said it launched an investigation after receiving a single report of charging problems with the device, which debuted earlier this year.

The problem deals another setback to Humane, a high-profile startup that set out to build an alternative to the smartphone. Since launching in April, the Ai Pin has been criticised by customers and reviewers for its cumbersome interface and lack of features.

Following the troubled introduction, the startup contacted large technology companies and advisory firms in hopes of selling itself for several hundred million dollars, Bloomberg has reported.

The charging case, which works similarly to an AirPods case, is included in the package when a user buys the Ai Pin for US$699 and up. It’s also been sold as a standalone accessory for US$149 . The part is now marked as “out of stock” on Humane’s website.

“Our investigation determined that the battery supplier was no longer meeting our quality standards and that there is a potential that certain battery cells supplied by this vendor may pose a fire safety risk,” the company said in a statement posted Wednesday to its website. “As a result, we immediately disqualified this battery vendor while we work to identify a new vendor to avoid such issues and maintain our high quality standards.”

Humane said users can continue to charge the device with the included home charging dock. The company didn’t say if it will replace charging cases belonging to Ai Pin owners or how long it would take to find a replacement supplier. It’s giving Ai Pin owners two free months of the required monthly subscription in light of the problem.

 - Bloomberg