I have built the foundry (all buildings) but after the battery orders I now can't fill my orders as..

I was stuck for months until I figured out you have to reject orders until you get an order you can fill using your lithium batteries & battery cells. Unfortunately if you just reject & let the timer run out, it will default to motherboards, which you can’t produce yet because you’re still on level 1. The only way I could get orders I wanted was to spend diamonds until I got what I needed to level up. I only figured it out 72 hours ago but I’m moving along great now. It’s a $ grab for sure. You need diamonds to have a chance to get what you need.

You have to upgrade whichever building you need to produce an item that is blanked out & not available until level 5. When you click on the building there is a small arrow like icon in the right & you click on that & it will say at the bottom in yellow or gold how much money & building permits you will need to upgrade & after you upgrade to whichever level those items will be available for you to produce. One factory takes one permit & the other one takes 2. Hope that helped.

I just had to save up very slowly and painfully to upgrade my materials workshop to produce processing units, and then upgrade my packaging workshop as required.

To upgrade you need to select the unit you want, then select the tab with the up arrow on it, then you can see the button to upgrade.

You have to click on the building & then at the top theres a little symbol & u click on that & if u have one building permit & the money it can click upgrade & u can do them each a few times. It says capacity bonus on the upgrade page as well. & u can upgrade your warehouse too so u will have more room in there

Pay the required amount and upgrade to the next level. Like that you need to upgrade 3 times to reach to the motherboard level 5.