OK, you don't buy their claim that a 9V battery could damage something- go ahead and tell us about your qualifications. We'll wait.
Crossover caps are made to handle AC current, but you connected a 9V battery. If you don't believe that a 9V has much ability to damage things, push the terminals into a clump of steel wool and tell us what happens. If nothing happens, use a charged battery. If you want a quick personal experience, put a 9V battery in your pocket along with some coins. Tell us about that, too.
If you do the latter, don't blame me if you burn your leg and/or pants.
If your goal is to crap on A4L, it's best to not do it publicly, where they can be damaged by your acts and comments. We get it- you don't like them but if they're damaged/harmed by comments that are based on missing info, 'facts' that are inaccurate or falsehoods, expect to hear from them if they see what you have posted, especially if you posted about this incident on additional sites.
If your goal is to make people reconsider buying from A4L or to make them stop considering A4L, you have already harmed them, so you're on your own.
I read the customer comments back to 2021 and saw that several didn't read the manual (which is easy to find online) and rely on some unknown 'expert' for setup, info and opinions. That's a bad way to reach good results.
Shipping costs are stated on their website- I can't think of any company that covers shipping TO them, only FROM them after service or replacement. That's the way it has been for consumers and retailers since I started working for retailers in1972. At that time, there were very few 'direct to user' sellers and they didn't pay for return shipping, either. The manufacturers I shipped to when I worked for retailers didn't pay both ways, I have to pay (or charge customers) for shipping when equipment is sent to service locations and returns are paid up front unless a supplier wants to be generous. Not being in the industry, I wouldn't expect free stuff if I were you, but I would expect them to ask a lot of questions when claims of inoperability come in.
In all cases, RTFM before using or installing any electronic equipment. If you don't want to because you're all manly and beefy, don't expect this stuff to work properly, if at all.
If you don't like the tone of the messages coming from A4L, think about how you would act if you had to listen to customers whine and complain on a regular basis. Having said that, if you had tested the speakers with a proper AC signal and they didn't work, I guess they can be chalked up to 'shi& happens, sometimes'- nobody is perfect and shipping damage isn't always visible but communication only works when it actually happens. How something is stated makes a difference. If you teed off on the CS department before deciding that someone is bad employee, I would tell you that's the fastest way to not receiving special favors.