the module is NOW unselectable

"entry in system folder" -- what's that? You mean the source code directory for signup itself? Do you mean the row in the {system} table in your DB? It's hard to help you without lots more detail.

Anyway, as I mentioned at the other thread, your best bet would have been reverting your DB to your backup from before you started running update.php from signup update #1. This is only a test site, of course, why else would you be running a -dev snapshot from an unsupported branch on it? And, of course, you've got DB snapshots before you ever run update.php, as is recommended in the help text for update.php itself, and in all the documentation abut upgrading your site...

However, if you've thrown caution to the wind, and none of those things are true, then I hope this experience will encourage you to think twice about using -dev snapshots and the need for DB backups before update.php. :) All that said, here's what you can try to do:

A) Read the fine print next to the signup entry at admin/build/modules. There might be some explanatory text about why it's disabled. For example, if you've installed some other module that depends on signup.module, you won't be able to disable signup if the other one is still enabled.

B) Visit the "Uninstall" tab on the modules page: admin/build/modules/uninstall If it lets you, go ahead and try to "uninstall" signup. It'll probably throw some warning messages about failing to delete tables you've manually deleted, but so be it.

C) Completely remove your source code directory holding the signup module (e.g. sites/all/modules/signup if that's where you put it) and click "Save configuration" at the modules page (admin/build/modules).

Good luck,
-Derek

Please set this back to "active" and provide lots more detail if the above doesn't solve the problem. Otherwise, I'm going to call this "fixed" (and eventually, it'll move itself to "closed").

Thanks,
-Derek