What is your opinion of the allegations of fraud of Ethan Siegel (astrophysicist)?

I don't find all of Pomp's points convincing. Many of them are suggestive, which is not helpful.

Arguing that Pomp is biassed and therefore his points should be rejected is wrong: points can be considered on their own merits regardless of who articulated them.

This latest test is interesting in that there are various ways in which it is not as rigorous as any scientist would require to back a new and not yet hypothesised theory. In this case we don't even have a viable LENR theory to explain the presumed set of nuclear reactions that could so completely transform Ni to 62Ni while emitting constant power.

it is even more interesting because it contains internal inconsistencies that appear to explain the high apparent COP on the hypothesis that Rossi's reactor is an electric heater and nothing else.

So if we look only at this latest test we would have to say there is no evidence in it for Rossi having LENR other than the astonishing 62Ni ash.

Still, after the test with measured Cu contaminated ash Rossi did afterwards say that he thought the contamination was due to him, and not from the reaction. In this case perhaps he will do the same?

In my opinion the scientists did a credible job trying to prove if there was or was not something worth consideration. No test is perfect and all tests can be make better in retrospect including this one. I see no evidence that would make one not want to further pursue this phenomenon. Ignore everything but the data. the 62Ni and the COP could be wrong but are more likely correct in that the quality of the test was high enough to preclude most possible errors. So I would say we need to move on and see more tests and more prototype devices and some replications, Like all theories this will or will not stand the test of time. Opinions and rhetoric are not the way to the truth, the fact that something does not do what is expected does not make it impossible.

The Ni-62 testing is almost certain correct. Whether the sample tested was the ash from the fuel tested is another matter and about probabilities of fraud vs highly unusual results. A matter of judgement.

The COP tests come with built-in inconsistencies. Of course its possible in principle there is a variable resistance heating element but that would be be most coincidental (resistance identical for two active tests whilst very different for dummy test) as well as unusual. The evidence to resolve this is in the data taken from the tests. Until that is used more fully, so allowing the resistance of the heating element vs temperature to be checked, the COP data is useless.

The testers can easily do this additional checking of the data and present the results to resolve any anomaly. If they don't do this it must be assumed that the COP test is wrong. That would alter probabilities of fraud vs extraordinary (even by LENR standards) nuclear conversion. How much is also a matter of judgement.

If you ask me what is the simplest explanation? That would be: substituted bought Ni-62, which would explain both the isotopic and the chemical chnage between fuel and ash. Clamp reversal or some other setting change to give 1/3 under-reading of power in active test, this making COP 1.2 and within experimental error (there are issues about the Al2O3 optical characteristic assumptions). Rossi clearly had access enough to do both things so that is all that is needed.

Acording to Appendix 4 in the report, The ICP-MS & ICP-AES analysed a sample of ash
of mass 2,13 mg.

This is analyzing bulk elements. The other types of analysis was surface
measurements of ash grains (I believe..)

SO: Assuming the total ash content is around 1000 mg, then this analysis is based on 0,21 %
of total ash weight.

How anyone can base any types of conclusions on 0,2 weight% of material beats me.

Most likely this 0,2% sample is not representative of the total.

The isotopic results are unambiguous even on a tiny sample. There is no chemical process that could enrich Ni to 98% Ni-62. In fact such enrichment is very tedious, takes a lot of steps. So if 1mg is 98% enriched then we have isotopic change.

There is only the atomic weight difference to get leverage on when enriching for a given isotope. You can do this in a mass spectrometer, or very slowly via diffusion.

The fact that this sample is almost pure Ni could perhaps be some chemical process - but not easy to see how. Entropy does not like pure things so to go from a mixture to a pure element in a closed reactor is not normal.