How to unleash R350 Access Point (newcomer)?

[CDuv]

Hello,

I've got my hand on a couple of used R350 Access Point I wish to use without external controller (I'm used to UniFi products with their "Network controller" self-hostable software): I understand "Unleashed" (where it installs a controller on one AP) is the solution.

How do I install Unleashed?

1. I've downloaded the "RUCKUS Unleashed AP 200.19 (GA) Software Release for R350" from Software Downloads.
2. Accessed https://192.168.0.1
3. I've factory resetted the AP
4. Then re-accessed https://192.168.0.1
5. In the "Maintenance :: Upgrade" page, using "Local" Upgrade Method I've uploaded the "R350_200.19.7.11.283.bl7" file but I got (MD5 hash matches) an error:
   

   The following error occurred

   Bad header Magic. Possible reasons:file corrupted or data corruption during upload

I've found an old topic with similar issue where it recommands using TFTP upgrade via CLI (https://community.ruckuswireless.com/t5/Unleashed/R350-trouble-unleashing/m-p/70395) but I'm not sure it's relevant for my situation.

As it's an used device I don't know it's currently "managed" but according to "get version" CLI command (see below) it's "Hotzone Wireless AP".

Here are some CLI command outputs:

rkscli: get version
Ruckus R350 Multimedia Hotzone Wireless AP
Version: 6.1.2.0.2230

rkscli: get scg

------ SCG Information ------
SCG Service is enabled.
AP is not managed by SCG.
State: GETSVRIP
Server List: Not found
No SSH tunnel exists
Last Join Time : NA
Tunnel Uptime : NA
Total SSH Tunnel Establishments: 0
Failover List: Not found
Failover Max Retry: 2
DHCP Opt43 Code: 6
Server List from DHCP (Opt43/Opt52): Not found
SCG default URL: RuckusController
SCG config|heartbeat intervals: 30|30
SCG gwloss|serverloss timeouts: 1800|7200
Controller Cert Validation : disable
-----------------------------

What are my options?