I know there could be a lot of effort put into opening packs quickly tonight to try and get lower serials. With that in mind here is a quick guide to open them manually, in case any glitches pop up on the pixelboosters.com website.
Step 1: Transfer the booster pack NFT to "phbank" with the memo "unbox" (do not use the quotation marks). NOTE: If you already transferred the NFT using the Open button on pixelboosters.com you just need to claim your cards and can skip to step 2:
Find your username and copy the pack_asset_id (2nd column, should look something like this: 4398046712083)
In the pack_asset_id spot paste in the number you copied in step 2
In the origin_rolls_id spot put in "[0,1,2]" without the quotation marks