Wow! Sounds like trouble.
I just finished a Berliner that was created via the handful of malt method that is incredible. There is a lot to be said for using more than a monoculture in your sour beer. Here is what I did:
1.5L of 1.030 starter wort in 2L erhlenmeyer flask.
Pitched with handful of Best Pils malt (whole).
Capped with tightly fitting sheet of aluminum foil (didn't have a stopper to fit the flask!)
Wrapped with heating pad and kept at around 100F.
Smelled pretty funky for a few days
Dusty, chalky looking pellicle formed. Was easily swirled away with agitation.
Became nicely smooth and tart smelling after about 5 days
Final pH: 3.1
Created 5 gal of 50/50 Pils/Wheat wort with single step at 154F
Ran off hot wort into 5 gal corny keg.
Installed keg lid and allowed to cool to 100F overnight.
Pitched entire starter (above) and replaced lid.
Wrapped heating pad and blanket around keg and kept at around 100F
Vented keg daily, lacto does NOT produce much CO2, so the venting was minimal.
Smelled like a sewer...funky for a couple of days.
Cleaned up to a smooth and tart aroma after about 5 days
Final pH: 3.1
Poured soured wort into kettle, produced a huge, dense head.
Boiled the 5 gal of soured wort for 1 hour, wanted to make sure DMS from Pils was gone.
Very fruity, pleasing aroma throughout.
About 10 IBU of early hopping applied.
Transferred hot wort directly into fermenter and allowed to cool overnight
Direct pitched packet of US-05 yeast into fermenter at 68F.
Took about 12 hours to show signs of airlock activity.
Fermented slowly for about 5 days...low pH and low gravity probably the reason.
Finished around 1.010, didn't want to let it go too low since I figured the beer needed a little sweetness to counter the acidity.
Very nice, multi-dimensional flavor, very clean and tart. Met with high regard from my club's National and Master judges. By my palate, this was equal to the Berliner's that I've tasted from Fritz Briem 1854 and Berliner Kindle. Mission accomplished!
I feel that an important lesson here is that it is VERY important to prevent oxygen contact with the bacterial culture since that can invite truly funky and off aroma and flavor. Give the culture time and the lacto will eventually out-compete the other organisms and severely limit their activity via the low pH from their lactic acid production. Note that the keg of wort hit with the lacto starter still went funky, so those other organisms were still lurking in that starter. The lacto still out-competed them and produced a great result.
I've tasted the Wyeast Berliner's at the past couple of AHA conferences and have to say that they are quite bland and uninspiring. This multi-organism starter definitely helps avoid that problem. Those of you that have read the Bru'n Water Facebook page know that you can improve the depth of a Berliner's acid flavor by adding distilled vinegar to infuse a low level of acetic acid that is present in a good Berliner. But I'd say that this 'natural' approach does produce a more pleasing complexity and depth.
By starting with a starter, you can avoid wasting a whole batch of beer. Just let that thing go through it's funky phases and eventually it should develop that pleasing sourness and smooth tartness from lactic acid. As noted, this is not a terribly rapid process, but it does work and the result can be outstanding.