ABS likes to cool on its own. Turn off the fan for the first few layers. I like to wait until 3mm before turning the fan on to 50% or 60%. Anything more can again cause the ABS to contract as it cools.
Keep the bed temp at 110C for the first few layers also. Drop to 95-100C for the duration of the print.
Lowering the nozzle will probably help. A picture of the bottom could help us critique the initial nozzle distance. Can you remove the brim without scraping? If you can, I’d say you need to get the nozzle lower. In S3D, use a -.1 to -.2 Z-offset under the “GCode” Tab. Make sure to have a tool handy to get under the print… Lowering the nozzle could make the print stick too well to the PEI.
Another fix may be to give the PEI a little sanding using a fine grit.
And finally. If it still warps, try a temporary enclosure to trap heat. A blanket covering the printer can work, make sure it doesn’t interfere with the print.
Hope this helps.