After the first couple times inserting the battery and figuring out how to insert them correctly, the battery insertion was fine. Before figuring that out I tore a couple of battery sleeves, but those were easy enough to replace.
My primary complaints are that the powder coating is terrible and it was large, boxy, and heavy. Wasn't a great mod to just throw in your pocket and go imo. But other than that, it worked great. I definitely wouldn't consider it a heap of shit. I did sell mine because I wanted to replace it with something smaller.
Any advice please.
Do both batteries work in another mod? Are you sure you're always inserting both batteries correctly (both batteries go positive terminal up)? Are the positive and negative terminals of the battery and the posts in the sled clean? Make sure there is nothing in the way of either terminals and battery posts and that they batteries making a clean connection.
Try putting one battery in the inner part of the sled and see if it turns on. Then take it out and put the other battery in the inner part of the sled and see if it turns on. Then try the each battery in the outer side of the sled. If one battery doesn't work in either part of the sled then you might have a defective battery or you aren't inserting it properly. If both batteries work in both parts of the sled then it's likely user error somewhere when you're inserting both batteries. If both batteries don't work in a particular slot in the sled then there's likely a wire loose somewhere and you need to do some soldering work to fix it.... or again, user error. You could also rule a lot of this out with a multimeter if you have one.
If you are confident you're inserting the batteries so they're making a solid connection to the terminals and you don't think you can fix it yourself you might want to take it to someone who knows how to fix electronics or get in touch with Lost Vapes to see if they'll do warranty work on it. They should, considering they have a six month warranty and you've had it for only three months (they have a US based repair center, but no idea if they have one in the UK so you might have to reach out to them directly). Evolv might even help you, but idk, might be worth a shot to reach out to both.
Hope you figure it out.