Returns declined because of broken seal

I bought the Yobolife Solar Lighting System Lithium-Ion/LifePo4 With Panels because l wanted to use the solar system to charge my phone.

I opened the box and used the power station for 2 days and on both days it only charged on 25% and 50%. After realising that it doesn't charge fully and that it take the whole day for it to reach up to 50% on a sunny day l requested a return and refund because it does not work properly. It doesn't meet my requirements as it's failing to charge the LifePO4 lithium battery that should charge quickly. Now I'm struggling to get my money back and product was returned before 7 days. I sealed the box upon returns and gave it to the driver. I surely should qualify for a refund as l have stated my reasons above.