Batch 9 DIY laptop won't power on

My Batch 9 DIY laptop worked well about a month ago. I hadn’t used it for a couple of weeks and the battery is completely out of energy. I have tried to charge it up using the phone USB-C on the right side, using the laptop charger on the left, but nothing happens and the orange light does not come on. What can I do?

Check out the steps here.