I have had this Manker U21 and i loved this light and used it every night to walk my dogs,untill it died ,so cjecked to make sure everything was secure without disassembling light.Still nothing,i tried all my batteries and still nothibg so i emailed outdoor gear sales rep Alan i asked if i could get an rma to return it under warranty and right away Alan started giving me resistance.He told me to send pictures of my battereis which were new awt 4200 mah 75 amp draw (i know its not) and he told me my batterries were insufficient to power the U21 so i tried some keepower 4200 mah and he said they were insuffiecient to power the light,so when i asked him why did it work before and not now and again he blamed my batterries he sent me a picture of Vappower 5200mah 30 amp would would be sufficient ,so i again taking his word i orderd and received keepiwer 5200mah 40 amp and i charged them at 2.00 amp on my opus 3400 smart charger and waited untill they were fully charged and still nothing this whole in between time waiting for batteries i kept emailing him asking why cant they just take it under factory warrantyand he kept giving me the runaround and was never willing to give an return authorization so tjen he sent me this Dear,
Thanks for your message.
Could you please make a video to us firstly. you can send it to our email or upload to YouTube. I will ask the factory engineer to watch it and then I will offer our best solution to you. if the factory engineer can not resolve it, I will be responsible for your order.
Kind Regards
Alan Gan
He is acting like if it is coming out of his pocket,does anyone have any suggestions ?All i wanted was a functional light