At first I thought it might be a problem with the flash firmware update, but after checking that the latest firmware was already installed, it was confirmed that the device was defective. It uses 2 available May 2600 batteries in less than 20 minutes. Also, the flash has a long (10 seconds) delay when used at close range. It's too awkward waiting for the flash when you're trying to capture different poses in a row. I would not recommend this product. I have a few newer brand flashes that work perfectly and this flash can't compete with the newer flash which is available for less than half the price of this brand from Godox.