Unresolved What could be causing this odd ABS warping issue?

No, you have to modify the Robo firmware (download from here:http://guide.robo3d.com/Wiki/ROBO_3D_Firmware_Release_Notes) and re-upload it,

 

Then heat management is the problem.
ABS is difficult to print correctly w/o a heated chamber.

If the bottom is curling ABS 'juice' might be a good tool to use for keeping the first layer bonded to the bed.

Other layers warping and curling is purely due to too rapid cooling of the filament/model.

@Printed Solid has the enclosure for the Robo which certainly can help, I had some luck using directed heat -- specifically small IR heat lamps directed at the model printing. However you are going to need to experiment. The way ABS as a material behaves is a known quantity. As I mentioned there are very likely other materials that will give you better properties and not suffer the heat management issues, but they are going to cost more.

 

As a comparison point, I have as I mentioned printed a decent amount of ABS (3 spools) on my robo, but I was never able to 100% get rid of warp and curl with ABS. 95% or so was about the best I could do. I just worked with it and adapted the models, but since the new plethora of materials has come out much with better properties I have not used ABS in over a year.

 

All of them work well (except for ABS) but my favorite is either allow 910 or PCTPE

although In-PLA is really nice as well (if you can live with PLA properties).

I have had no issues with any of the Nylons either. They are susceptible to minor warp, but frankly with some tuning of the bed and nozzle temperatures you can get that gone 99.9%.

Seriously for ABS the real killer is minor drafts and other air movement which is almost impossible to control without a heated chamber. The cover that @Printed Solid carries goes a long way towards helping that if you really MUST use ABS. I would suggest examining some of the other materials.

 

Even my biggest and best ABS prints had warp and minor curling that I could never completely eliminate.

 

If you make sure the printer is isolated from drafts (also make certain the parts fan stays OFF) and is in an area that has stable temperature environment you can probably get it printing again. I was at best able to get decent prints, just never perfect ones. The extra effort was what made me give it up. My time is worth more than that.

 

You can experiment.
This is one thing I did with (90%) ABS:

http://www.thingiverse.com/make:90476

but you can see that it had minor warp on the parts (look closely at the seams between the sections) and this was the best I could do. That was mostly white, and some black ABS.

You can get decent results with ABS, but it takes a lot of luck or a lot of tuning/tweaking.
Missing the heated enclosure is a big down-side for that material.