Please find above your basic service manual.
Hi, I am sorry to tell you this but my diagnosis, is that this is a fairly classic "Hic-upping" switchmode power supply problem. The protection circuitry inside the SMPSU, has sensed a severe potential problem, and is attempting/has/is shutting the set, down to avoid a fire, explosion, or both.
This set had developed a problem, that is so severe that the set must be shut down, (This set should be removed from the Power),
What is happening is the internal "Fault" that is causing the Protection Circuitry, to detect the problem and attempt to shut down the set, the set then keeps restarting, because as soon as it shuts down, the "Faulty" component(s) cool down? but whatever, and the "Fault" then ostensibly "Clears", so the PSU then starts up again, only for the component(s) to heat up again, whatever, and again fail, so it once again, shuts down. Now if we left this on & unattended, this would then continue on until the part eventually failed.
As related this is called a "Hic-upping Power Supply". Any fault that involves the power supply is usually quite serious, and needs a professional, usually, unless one is familiar with servicing current day, televisions.
And in my professional recommendation, you should get a "Quote" for repair, from, an, Approved Service Center. Now, this point is very important for a good result, Always contact, their "Local" or a, "Head Office" Loewe in your case. Ask them, for a referral to an authorised servicing center, where you ask for a "Quote". Now, when you get the information you want, then you can decide as to repair of replacement.
The reason we want an approved agent, is that way, all the engineers are trained on their own brand sets, they have seen almost all faults, and will get the job done quicker, and for less cost, and usually have parts on hand, also sometimes, there has been a service bulletin in issued and the repair may be subsided or even free. There are many, many, many reasons that display this symptom, one must work through the troubleshooting steps to isolate and identify, the Cause and repair that and any damage done.
OK well what has happened i suspect, is that your set has been "Spiked" from a power disturbance, and this has damaged either the PSU, or an internal high voltage component, or both, and now, the Protection Circuitry in the SMPS unit, is "Sensing" a potential "Catastrophic fault", that may cause a fire an explosion or both, and accordingly the set MUST be shut down, so the protection circuitry does exactly that.
Your best bet, is to contact a local or head office of the TV's manufacturer, and ask them for a referral to an authorised servicing center. When contact is made with them, ask for a "Quote" for the repair, before allowing any repair work to be undertaken. This then at least will give you an idea as to costings and you can then make an informed decision as to repair or replace, as often these days i find in my shop anyway, many repairs can be very expensive, and often it would be better putting any monies that would have been spent on repair towards a NEW unit with a warranty.
However if you do wish to DIY, then I have also included a copy of a service manual, which is essential. Start at the troubleshooting section and work through the steps. remember we always start with the Power Supply voltages, as if they aren't correct there, at the connected/ disconnected PSU, then nowhere else can have the correct voltages, and hence will not work correctly. We then work "down the faulty rail" until we find the fault. remember usually we have the faulty component AND any damaged ones, to actually "Fix" it, or else the fault will simply come back.
There is also the "Shotgun" method as we engineers call it, that is basically replace all suspected boards, ad hoc, BUT remember if doing this again the PSU VOLTAGES MUST BE OK, or you will simply destroy the newly connected replacement board.