dheeni - You don't list what Security Remote(s) you have. You can only disarm the system with a remote. For this test, I'll assume you have a KR10A KeyChain remote. The SH624 also works for this, but remember the MS10A is only "armed" when you ARM-AWAY, when you ARM-HOME, they will NOT trip the alarm.
Back to the beginning. For a test:
Unplug the console & remove the battery.
Set the H/C of the Console to "L" and set the UnitCode U/C to "5"
Set a lamp module to L5.
Plug a lamp into the L5 module.
Plug the L5 lamp module into a 2-plug wall socket - the same socket you're going to plug the console into.
Manually turn the lamp ON.
Plug in the console to the same wall socket.
You should now have both the L5 module (with the light ON) and the console plugged into the same 2-plug wall socket. Don't use extension cords or power strips.
Move the Install/Run-1/Run-2 switch to INSTALL.
Press the button on the back of the MS10A. The console should "DING" and the first position's red LED should come on. Set the 1-2 switch on the back of the MS10A to "1"
Press the DISARM button on the KR10A keychain remote. The console should "DING" to indicate it was registered.
Move the Install/Run-1/Run-2 switch to RUN-1. The top red LED (indicating where you installed the MS10A) should go out.
Press the ARM button on the keychain remote. The console should "DING" and the red ARM LED should light.
Create movement in front of the MS10A until its red LED flashes on & off.
The alarm should sound and the lamp should go on and off.
If you've programmed the dialer, the console should make the call.
If you do nothing, the alarm should sound for 4 minutes then stop & reset itself.
If you press DISARM on the KR10A, the alarm should stop, the light (L5) should be on, and the top red LED (where you installed the MS10A) should be on,and the ARMed LED should be flashing on the console. Pressing Lights-OFF on the KR10A should turn L5, and the console's red LED's off.
At any time (except during an alarm) pressing LIGHTS-ON on the KR10A should light the L5 lamp (and all other lamps addressed to L5).
IF that worked - move the L5 module & lamp to a different socket and see if the KR10A Lights-ON & Lights-OFF works. The console is picking up the RF from the KR10A and TRANSCEIVING the signal into PLC (PowerLineCommands) - and sending them out over its power cord and through your house wiring to the L5 module(s). If you move the L5 module to a socket where the light DOESN't turn on & off either by the alarm sequence, or by pressing the KR10A's buttons, then you have a signal strength or a PHASE problem - (read about them elsewhere in this forum).
If moving your L5 lamp & module around works OK, set the address of the SH10A to L5 (same as the lamp) and plug it into a socket where you've successfully tested the lamp.
Put in your ear plugs! No, I'm not kidding.
Arm the console and trip the alarm. While the L5 Lamp is flashing on & off, the PowerHorn should start up. Sometimes it takes a few seconds before it gets going.
If the PowerHorn is addressed the same "L5" and it's plugged into a KNOWN good socket (where the lamp did work), and if the lamp at L5 is flashing on & off - if the PowerHorn stays quiet, you have a defective PowerHorn.